🏗 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/ethernet/__init__.py

@@ -0,0 +1,101 @@
+from esphome import pins
+import esphome.config_validation as cv
+import esphome.codegen as cg
+from esphome.const import CONF_DOMAIN, CONF_ID, CONF_MANUAL_IP, CONF_STATIC_IP, CONF_TYPE, \
+    CONF_USE_ADDRESS, ESP_PLATFORM_ESP32, CONF_GATEWAY, CONF_SUBNET, CONF_DNS1, CONF_DNS2
+from esphome.core import CORE, coroutine_with_priority
+
+CONFLICTS_WITH = ['wifi']
+ESP_PLATFORMS = [ESP_PLATFORM_ESP32]
+
+ethernet_ns = cg.esphome_ns.namespace('ethernet')
+CONF_PHY_ADDR = 'phy_addr'
+CONF_MDC_PIN = 'mdc_pin'
+CONF_MDIO_PIN = 'mdio_pin'
+CONF_CLK_MODE = 'clk_mode'
+CONF_POWER_PIN = 'power_pin'
+
+EthernetType = ethernet_ns.enum('EthernetType')
+ETHERNET_TYPES = {
+    'LAN8720': EthernetType.ETHERNET_TYPE_LAN8720,
+    'TLK110': EthernetType.ETHERNET_TYPE_TLK110,
+}
+
+eth_clock_mode_t = cg.global_ns.enum('eth_clock_mode_t')
+CLK_MODES = {
+    'GPIO0_IN': eth_clock_mode_t.ETH_CLOCK_GPIO0_IN,
+    'GPIO0_OUT': eth_clock_mode_t.ETH_CLOCK_GPIO0_OUT,
+    'GPIO16_OUT': eth_clock_mode_t.ETH_CLOCK_GPIO16_OUT,
+    'GPIO17_OUT': eth_clock_mode_t.ETH_CLOCK_GPIO17_OUT,
+}
+
+
+MANUAL_IP_SCHEMA = cv.Schema({
+    cv.Required(CONF_STATIC_IP): cv.ipv4,
+    cv.Required(CONF_GATEWAY): cv.ipv4,
+    cv.Required(CONF_SUBNET): cv.ipv4,
+    cv.Optional(CONF_DNS1, default="0.0.0.0"): cv.ipv4,
+    cv.Optional(CONF_DNS2, default="0.0.0.0"): cv.ipv4,
+})
+
+EthernetComponent = ethernet_ns.class_('EthernetComponent', cg.Component)
+IPAddress = cg.global_ns.class_('IPAddress')
+ManualIP = ethernet_ns.struct('ManualIP')
+
+
+def validate(config):
+    if CONF_USE_ADDRESS not in config:
+        if CONF_MANUAL_IP in config:
+            use_address = str(config[CONF_MANUAL_IP][CONF_STATIC_IP])
+        else:
+            use_address = CORE.name + config[CONF_DOMAIN]
+        config[CONF_USE_ADDRESS] = use_address
+    return config
+
+
+CONFIG_SCHEMA = cv.All(cv.Schema({
+    cv.GenerateID(): cv.declare_variable_id(EthernetComponent),
+    cv.Required(CONF_TYPE): cv.one_of(*ETHERNET_TYPES, upper=True),
+    cv.Required(CONF_MDC_PIN): pins.output_pin,
+    cv.Required(CONF_MDIO_PIN): pins.input_output_pin,
+    cv.Optional(CONF_CLK_MODE, default='GPIO0_IN'): cv.one_of(*CLK_MODES, upper=True, space='_'),
+    cv.Optional(CONF_PHY_ADDR, default=0): cv.All(cv.int_, cv.Range(min=0, max=31)),
+    cv.Optional(CONF_POWER_PIN): pins.gpio_output_pin_schema,
+    cv.Optional(CONF_MANUAL_IP): MANUAL_IP_SCHEMA,
+    cv.Optional(CONF_DOMAIN, default='.local'): cv.domain_name,
+    cv.Optional(CONF_USE_ADDRESS): cv.string_strict,
+
+    cv.Optional('hostname'): cv.invalid("The hostname option has been removed in 1.11.0"),
+}), validate)
+
+
+def manual_ip(config):
+    return cg.StructInitializer(
+        ManualIP,
+        ('static_ip', IPAddress(*config[CONF_STATIC_IP].args)),
+        ('gateway', IPAddress(*config[CONF_GATEWAY].args)),
+        ('subnet', IPAddress(*config[CONF_SUBNET].args)),
+        ('dns1', IPAddress(*config[CONF_DNS1].args)),
+        ('dns2', IPAddress(*config[CONF_DNS2].args)),
+    )
+
+
+@coroutine_with_priority(60.0)
+def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+
+    cg.add(var.set_phy_addr(config[CONF_PHY_ADDR]))
+    cg.add(var.set_mdc_pin(config[CONF_MDC_PIN]))
+    cg.add(var.set_mdio_pin(config[CONF_MDIO_PIN]))
+    cg.add(var.set_type(ETHERNET_TYPES[config[CONF_TYPE]]))
+    cg.add(var.set_clk_mode(CLK_MODES[config[CONF_CLK_MODE]]))
+    cg.add(var.set_use_address(config[CONF_USE_ADDRESS]))
+
+    if CONF_POWER_PIN in config:
+        pin = yield cg.gpio_pin_expression(config[CONF_POWER_PIN])
+        cg.add(var.set_power_pin(pin))
+
+    if CONF_MANUAL_IP in config:
+        cg.add(var.set_manual_ip(manual_ip(config[CONF_MANUAL_IP])))
+
+    cg.add_define('USE_ETHERNET')