🏗 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/custom/output/__init__.py

@@ -0,0 +1,63 @@
+from esphome.components import output
+import esphome.config_validation as cv
+import esphome.codegen as cg
+from esphome.const import CONF_ID, CONF_LAMBDA, CONF_OUTPUTS, CONF_TYPE
+from .. import custom_ns
+
+CustomBinaryOutputConstructor = custom_ns.class_('CustomBinaryOutputConstructor')
+CustomFloatOutputConstructor = custom_ns.class_('CustomFloatOutputConstructor')
+
+BINARY_SCHEMA = cv.Schema({
+    cv.GenerateID(): cv.declare_variable_id(CustomBinaryOutputConstructor),
+    cv.Required(CONF_LAMBDA): cv.lambda_,
+    cv.Required(CONF_TYPE): 'binary',
+    cv.Required(CONF_OUTPUTS):
+        cv.ensure_list(output.BINARY_OUTPUT_SCHEMA.extend({
+            cv.GenerateID(): cv.declare_variable_id(output.BinaryOutput),
+        })),
+})
+
+FLOAT_SCHEMA = cv.Schema({
+    cv.GenerateID(): cv.declare_variable_id(CustomFloatOutputConstructor),
+    cv.Required(CONF_LAMBDA): cv.lambda_,
+    cv.Required(CONF_TYPE): 'float',
+    cv.Required(CONF_OUTPUTS):
+        cv.ensure_list(output.FLOAT_OUTPUT_SCHEMA.extend({
+            cv.GenerateID(): cv.declare_variable_id(output.FloatOutput),
+        })),
+})
+
+
+def validate_custom_output(value):
+    if not isinstance(value, dict):
+        raise cv.Invalid("Value must be dict")
+    if CONF_TYPE not in value:
+        raise cv.Invalid("type not specified!")
+    type = cv.string_strict(value[CONF_TYPE]).lower()
+    value[CONF_TYPE] = type
+    if type == 'binary':
+        return BINARY_SCHEMA(value)
+    if type == 'float':
+        return FLOAT_SCHEMA(value)
+    raise cv.Invalid("type must either be binary or float, not {}!".format(type))
+
+
+CONFIG_SCHEMA = validate_custom_output
+
+
+def to_code(config):
+    type = config[CONF_TYPE]
+    if type == 'binary':
+        ret_type = output.BinaryOutputPtr
+        klass = CustomBinaryOutputConstructor
+    else:
+        ret_type = output.FloatOutputPtr
+        klass = CustomFloatOutputConstructor
+    template_ = yield cg.process_lambda(config[CONF_LAMBDA], [],
+                                        return_type=cg.std_vector.template(ret_type))
+
+    rhs = klass(template_)
+    custom = cg.variable(config[CONF_ID], rhs)
+    for i, conf in enumerate(config[CONF_OUTPUTS]):
+        out = cg.Pvariable(conf[CONF_ID], custom.get_output(i))
+        yield output.register_output(out, conf)