🏗 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/text_sensor/__init__.py

@@ -1,65 +1,57 @@
-import voluptuous as vol
-
+import esphome.codegen as cg
+import esphome.config_validation as cv
 from esphome import automation
 from esphome.components import mqtt
-from esphome.components.mqtt import setup_mqtt_component
-import esphome.config_validation as cv
-from esphome.const import CONF_ICON, CONF_ID, CONF_INTERNAL, CONF_MQTT_ID, CONF_ON_VALUE, \
-    CONF_TRIGGER_ID
-from esphome.core import CORE
-from esphome.cpp_generator import Pvariable, add
-from esphome.cpp_types import App, Nameable, Trigger, esphome_ns, std_string, Action
+from esphome.const import CONF_ICON, CONF_ID, CONF_INTERNAL, CONF_ON_VALUE, \
+    CONF_TRIGGER_ID, CONF_MQTT_ID
+from esphome.core import CORE, coroutine
 
-PLATFORM_SCHEMA = cv.PLATFORM_SCHEMA.extend({
-
-})
+IS_PLATFORM_COMPONENT = True
 
 # pylint: disable=invalid-name
-text_sensor_ns = esphome_ns.namespace('text_sensor')
-TextSensor = text_sensor_ns.class_('TextSensor', Nameable)
+text_sensor_ns = cg.esphome_ns.namespace('text_sensor')
+TextSensor = text_sensor_ns.class_('TextSensor', cg.Nameable)
 TextSensorPtr = TextSensor.operator('ptr')
-MQTTTextSensor = text_sensor_ns.class_('MQTTTextSensor', mqtt.MQTTComponent)
 
 TextSensorStateTrigger = text_sensor_ns.class_('TextSensorStateTrigger',
-                                               Trigger.template(std_string))
-TextSensorPublishAction = text_sensor_ns.class_('TextSensorPublishAction', Action)
+                                               cg.Trigger.template(cg.std_string))
+TextSensorPublishAction = text_sensor_ns.class_('TextSensorPublishAction', cg.Action)
+
+icon = cv.icon
 
 TEXT_SENSOR_SCHEMA = cv.MQTT_COMPONENT_SCHEMA.extend({
-    cv.GenerateID(CONF_MQTT_ID): cv.declare_variable_id(MQTTTextSensor),
-    vol.Optional(CONF_ICON): cv.icon,
-    vol.Optional(CONF_ON_VALUE): automation.validate_automation({
+    cv.OnlyWith(CONF_MQTT_ID, 'mqtt'): cv.declare_variable_id(mqtt.MQTTTextSensor),
+    cv.Optional(CONF_ICON): icon,
+    cv.Optional(CONF_ON_VALUE): automation.validate_automation({
         cv.GenerateID(CONF_TRIGGER_ID): cv.declare_variable_id(TextSensorStateTrigger),
     }),
 })
 
-TEXT_SENSOR_PLATFORM_SCHEMA = PLATFORM_SCHEMA.extend(TEXT_SENSOR_SCHEMA.schema)
 
-
-def setup_text_sensor_core_(text_sensor_var, config):
+@coroutine
+def setup_text_sensor_core_(var, config):
     if CONF_INTERNAL in config:
-        add(text_sensor_var.set_internal(config[CONF_INTERNAL]))
+        cg.add(var.set_internal(config[CONF_INTERNAL]))
     if CONF_ICON in config:
-        add(text_sensor_var.set_icon(config[CONF_ICON]))
+        cg.add(var.set_icon(config[CONF_ICON]))
 
     for conf in config.get(CONF_ON_VALUE, []):
-        rhs = text_sensor_var.make_state_trigger()
-        trigger = Pvariable(conf[CONF_TRIGGER_ID], rhs)
-        automation.build_automations(trigger, [(std_string, 'x')], conf)
+        trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
+        yield automation.build_automation(trigger, [(cg.std_string, 'x')], conf)
 
-    setup_mqtt_component(text_sensor_var.Pget_mqtt(), config)
-
-
-def setup_text_sensor(text_sensor_obj, config):
-    if not CORE.has_id(config[CONF_ID]):
-        text_sensor_obj = Pvariable(config[CONF_ID], text_sensor_obj, has_side_effects=True)
-    CORE.add_job(setup_text_sensor_core_, text_sensor_obj, config)
+    if CONF_MQTT_ID in config:
+        mqtt_ = cg.new_Pvariable(config[CONF_MQTT_ID], var)
+        yield mqtt.register_mqtt_component(mqtt_, config)
 
 
+@coroutine
 def register_text_sensor(var, config):
     if not CORE.has_id(config[CONF_ID]):
-        var = Pvariable(config[CONF_ID], var, has_side_effects=True)
-    add(App.register_text_sensor(var))
-    CORE.add_job(setup_text_sensor_core_, var, config)
+        var = cg.Pvariable(config[CONF_ID], var)
+    cg.add(cg.App.register_text_sensor(var))
+    yield setup_text_sensor_core_(var, config)
 
 
-BUILD_FLAGS = '-DUSE_TEXT_SENSOR'
+def to_code(config):
+    cg.add_define('USE_TEXT_SENSOR')
+    cg.add_global(text_sensor_ns.using)