🏗 Merge C++ into python codebase (#504)

## Description:

Move esphome-core codebase into esphome (and a bunch of other refactors). See https://github.com/esphome/feature-requests/issues/97

Yes this is a shit ton of work and no there's no way to automate it :( But it will be worth it 👍

Progress:
- Core support (file copy etc): 80%
- Base Abstractions (light, switch): ~50%
- Integrations: ~10%
- Working? Yes, (but only with ported components).

Other refactors:
- Moves all codegen related stuff into a single class: `esphome.codegen` (imported as `cg`)
- Rework coroutine syntax
- Move from `component/platform.py` to `domain/component.py` structure as with HA
- Move all defaults out of C++ and into config validation.
- Remove `make_...` helpers from Application class. Reason: Merge conflicts with every single new integration.
- Pointer Variables are stored globally instead of locally in setup(). Reason: stack size limit.

Future work:
- Rework const.py - Move all `CONF_...` into a conf class (usage `conf.UPDATE_INTERVAL` vs `CONF_UPDATE_INTERVAL`). Reason: Less convoluted import block
- Enable loading from `custom_components` folder.

**Related issue (if applicable):** https://github.com/esphome/feature-requests/issues/97

**Pull request in [esphome-docs](https://github.com/esphome/esphome-docs) with documentation (if applicable):** esphome/esphome-docs#<esphome-docs PR number goes here>

## Checklist:
  - [ ] The code change is tested and works locally.
  - [ ] Tests have been added to verify that the new code works (under `tests/` folder).

If user exposed functionality or configuration variables are added/changed:
  - [ ] Documentation added/updated in [esphomedocs](https://github.com/OttoWinter/esphomedocs).

esphome/components/stepper/__init__.py

@@ -1,23 +1,18 @@
-import voluptuous as vol
-
-from esphome.automation import ACTION_REGISTRY
+import esphome.codegen as cg
 import esphome.config_validation as cv
+from esphome.automation import ACTION_REGISTRY
 from esphome.const import CONF_ACCELERATION, CONF_DECELERATION, CONF_ID, CONF_MAX_SPEED, \
     CONF_POSITION, CONF_TARGET
-from esphome.core import CORE
-from esphome.cpp_generator import Pvariable, add, get_variable, templatable
-from esphome.cpp_types import Action, esphome_ns, int32
+from esphome.core import CORE, coroutine
 
-PLATFORM_SCHEMA = cv.PLATFORM_SCHEMA.extend({
-
-})
+IS_PLATFORM_COMPONENT = True
 
 # pylint: disable=invalid-name
-stepper_ns = esphome_ns.namespace('stepper')
+stepper_ns = cg.esphome_ns.namespace('stepper')
 Stepper = stepper_ns.class_('Stepper')
 
-SetTargetAction = stepper_ns.class_('SetTargetAction', Action)
-ReportPositionAction = stepper_ns.class_('ReportPositionAction', Action)
+SetTargetAction = stepper_ns.class_('SetTargetAction', cg.Action)
+ReportPositionAction = stepper_ns.class_('ReportPositionAction', cg.Action)
 
 
 def validate_acceleration(value):
@@ -32,10 +27,10 @@ def validate_acceleration(value):
     try:
         value = float(value)
     except ValueError:
-        raise vol.Invalid("Expected acceleration as floating point number, got {}".format(value))
+        raise cv.Invalid("Expected acceleration as floating point number, got {}".format(value))
 
     if value <= 0:
-        raise vol.Invalid("Acceleration must be larger than 0 steps/s^2!")
+        raise cv.Invalid("Acceleration must be larger than 0 steps/s^2!")
 
     return value
 
@@ -52,69 +47,65 @@ def validate_speed(value):
     try:
         value = float(value)
     except ValueError:
-        raise vol.Invalid("Expected speed as floating point number, got {}".format(value))
+        raise cv.Invalid("Expected speed as floating point number, got {}".format(value))
 
     if value <= 0:
-        raise vol.Invalid("Speed must be larger than 0 steps/s!")
+        raise cv.Invalid("Speed must be larger than 0 steps/s!")
 
     return value
 
 
 STEPPER_SCHEMA = cv.Schema({
-    vol.Required(CONF_MAX_SPEED): validate_speed,
-    vol.Optional(CONF_ACCELERATION): validate_acceleration,
-    vol.Optional(CONF_DECELERATION): validate_acceleration,
+    cv.Required(CONF_MAX_SPEED): validate_speed,
+    cv.Optional(CONF_ACCELERATION, default='inf'): validate_acceleration,
+    cv.Optional(CONF_DECELERATION, default='inf'): validate_acceleration,
 })
 
-STEPPER_PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(STEPPER_SCHEMA.schema)
-
 
+@coroutine
 def setup_stepper_core_(stepper_var, config):
     if CONF_ACCELERATION in config:
-        add(stepper_var.set_acceleration(config[CONF_ACCELERATION]))
+        cg.add(stepper_var.set_acceleration(config[CONF_ACCELERATION]))
     if CONF_DECELERATION in config:
-        add(stepper_var.set_deceleration(config[CONF_DECELERATION]))
+        cg.add(stepper_var.set_deceleration(config[CONF_DECELERATION]))
     if CONF_MAX_SPEED in config:
-        add(stepper_var.set_max_speed(config[CONF_MAX_SPEED]))
+        cg.add(stepper_var.set_max_speed(config[CONF_MAX_SPEED]))
 
 
-def setup_stepper(stepper_var, config):
-    CORE.add_job(setup_stepper_core_, stepper_var, config)
+@coroutine
+def register_stepper(var, config):
+    if not CORE.has_id(config[CONF_ID]):
+        var = cg.Pvariable(config[CONF_ID], var)
+    yield setup_stepper_core_(var, config)
 
 
-BUILD_FLAGS = '-DUSE_STEPPER'
-
-CONF_STEPPER_SET_TARGET = 'stepper.set_target'
-STEPPER_SET_TARGET_ACTION_SCHEMA = cv.Schema({
-    vol.Required(CONF_ID): cv.use_variable_id(Stepper),
-    vol.Required(CONF_TARGET): cv.templatable(cv.int_),
-})
-
-
-@ACTION_REGISTRY.register(CONF_STEPPER_SET_TARGET, STEPPER_SET_TARGET_ACTION_SCHEMA)
+@ACTION_REGISTRY.register('stepper.set_target', cv.Schema({
+    cv.Required(CONF_ID): cv.use_variable_id(Stepper),
+    cv.Required(CONF_TARGET): cv.templatable(cv.int_),
+}))
 def stepper_set_target_to_code(config, action_id, template_arg, args):
-    var = yield get_variable(config[CONF_ID])
-    rhs = var.make_set_target_action(template_arg)
+    var = yield cg.get_variable(config[CONF_ID])
     type = SetTargetAction.template(template_arg)
-    action = Pvariable(action_id, rhs, type=type)
-    template_ = yield templatable(config[CONF_TARGET], args, int32)
-    add(action.set_target(template_))
+    rhs = type.new(var)
+    action = cg.Pvariable(action_id, rhs, type=type)
+    template_ = yield cg.templatable(config[CONF_TARGET], args, cg.int32)
+    cg.add(action.set_target(template_))
     yield action
 
 
-CONF_STEPPER_REPORT_POSITION = 'stepper.report_position'
-STEPPER_REPORT_POSITION_ACTION_SCHEMA = cv.Schema({
-    vol.Required(CONF_ID): cv.use_variable_id(Stepper),
-    vol.Required(CONF_POSITION): cv.templatable(cv.int_),
-})
-
-
-@ACTION_REGISTRY.register(CONF_STEPPER_REPORT_POSITION, STEPPER_REPORT_POSITION_ACTION_SCHEMA)
+@ACTION_REGISTRY.register('stepper.report_position', cv.Schema({
+    cv.Required(CONF_ID): cv.use_variable_id(Stepper),
+    cv.Required(CONF_POSITION): cv.templatable(cv.int_),
+}))
 def stepper_report_position_to_code(config, action_id, template_arg, args):
-    var = yield get_variable(config[CONF_ID])
-    rhs = var.make_report_position_action(template_arg)
+    var = yield cg.get_variable(config[CONF_ID])
     type = ReportPositionAction.template(template_arg)
-    action = Pvariable(action_id, rhs, type=type)
-    template_ = yield templatable(config[CONF_POSITION], args, int32)
-    add(action.set_position(template_))
+    rhs = type.new(var)
+    action = cg.Pvariable(action_id, rhs, type=type)
+    template_ = yield cg.templatable(config[CONF_POSITION], args, cg.int32)
+    cg.add(action.set_position(template_))
     yield action
+
+
+def to_code(config):
+    cg.add_global(stepper_ns.using)