Event Loop 2.0 API and Windows implementation (#638)

* Rename EventsLoop and associated types to EventLoop

* Rename WindowEvent::Refresh to WindowEvent::Redraw

* Remove second thread from win32 backend

* Update run_forever to hijack thread

* Replace windows Mutex with parking_lot Mutex

* Implement new ControlFlow and associated events

* Add StartCause::Init support, timer example

* Add ability to send custom user events

* Fully invert windows control flow so win32 calls into winit's callback

* Add request_redraw

* Rename platform to platform_impl

* Rename os to platform, add Ext trait postfixes

* Add platform::desktop module with EventLoopExt::run_return

* Re-organize into module structure

* Improve documentation

* Small changes to examples

* Improve docs for run and run_return

* Change instances of "events_loop" to "event_loop"

* Rename MonitorId to MonitorHandle

* Add CHANGELOG entry

* Improve WaitUntil timer precision

* When SendEvent is called during event closure, buffer events

* Fix resize lag when waiting in some situations

* Update send test and errors that broke some examples/APIs

* Improve clarity/fix typos in docs

* Fix unreachable panic after setting ControlFlow to Poll during some RedrawRequested events.

* Fix crash when running in release mode

* Remove crossbeam dependency and make drop events work again

* Remove serde implementations from ControlFlow

* Fix 1.24.1 build

* Fix freeze when setting decorations

* Replace &EventLoop in callback with &EventLoopWindowTarget

* Document and implement Debug for EventLoopWindowTarget

* Fix some deadlocks that could occur when changing window state

* Fix thread executor not executing closure when called from non-loop thread

* Fix buffered events not getting dispatched

* Fix crash with runner refcell not getting dropped

* Address review feedback

* Fix CHANGELOG typo

* Catch panics in user callback

src/platform/android.rs

@@ -0,0 +1,38 @@
+#![cfg(any(target_os = "android"))]
+
+use std::os::raw::c_void;
+use EventLoop;
+use Window;
+use WindowBuilder;
+
+/// Additional methods on `EventLoop` that are specific to Android.
+pub trait EventLoopExtAndroid {
+    /// Makes it possible for glutin to register a callback when a suspend event happens on Android
+    fn set_suspend_callback(&self, cb: Option<Box<Fn(bool) -> ()>>);
+}
+
+impl EventLoopExtAndroid for EventLoop {
+    fn set_suspend_callback(&self, cb: Option<Box<Fn(bool) -> ()>>) {
+        self.event_loop.set_suspend_callback(cb);
+    }
+}
+
+/// Additional methods on `Window` that are specific to Android.
+pub trait WindowExtAndroid {
+    fn get_native_window(&self) -> *const c_void;
+}
+
+impl WindowExtAndroid for Window {
+    #[inline]
+    fn get_native_window(&self) -> *const c_void {
+        self.window.get_native_window()
+    }
+}
+
+/// Additional methods on `WindowBuilder` that are specific to Android.
+pub trait WindowBuilderExtAndroid {
+
+}
+
+impl WindowBuilderExtAndroid for WindowBuilder {
+}