🏗 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/remote_receiver/remote_receiver.h

@@ -0,0 +1,59 @@
+#pragma once
+
+#include "esphome/core/component.h"
+#include "esphome/components/remote_base/remote_base.h"
+
+namespace esphome {
+namespace remote_receiver {
+
+#ifdef ARDUINO_ARCH_ESP8266
+struct RemoteReceiverComponentStore {
+  static void gpio_intr(RemoteReceiverComponentStore *arg);
+
+  /// Stores the time (in micros) that the leading/falling edge happened at
+  ///  * An even index means a falling edge appeared at the time stored at the index
+  ///  * An uneven index means a rising edge appeared at the time stored at the index
+  volatile uint32_t *buffer{nullptr};
+  /// The position last written to
+  volatile uint32_t buffer_write_at;
+  /// The position last read from
+  uint32_t buffer_read_at{0};
+  bool overflow{false};
+  uint32_t buffer_size{1000};
+  uint8_t filter_us{10};
+  ISRInternalGPIOPin *pin;
+};
+#endif
+
+class RemoteReceiverComponent : public remote_base::RemoteReceiverBase, public Component {
+ public:
+  RemoteReceiverComponent(GPIOPin *pin) : RemoteReceiverBase(pin) {}
+  void setup() override;
+  void dump_config() override;
+  void loop() override;
+  float get_setup_priority() const override { return setup_priority::DATA; }
+
+  void set_buffer_size(uint32_t buffer_size) { this->buffer_size_ = buffer_size; }
+  void set_filter_us(uint8_t filter_us) { this->filter_us_ = filter_us; }
+  void set_idle_us(uint32_t idle_us) { this->idle_us_ = idle_us; }
+
+ protected:
+#ifdef ARDUINO_ARCH_ESP32
+  void decode_rmt_(rmt_item32_t *item, size_t len);
+#endif
+
+#ifdef ARDUINO_ARCH_ESP32
+  RingbufHandle_t ringbuf_;
+#endif
+#ifdef ARDUINO_ARCH_ESP8266
+  RemoteReceiverComponentStore store_;
+  HighFrequencyLoopRequester high_freq_;
+#endif
+
+  uint32_t buffer_size_{};
+  uint8_t filter_us_{10};
+  uint32_t idle_us_{10000};
+};
+
+}  // namespace remote_receiver
+}  // namespace esphome