Gamepad device events - Web/WASM (#1414)

Add gamepad support for stdweb and web-sys, as well as web-specific gamepad examples. 

* [web] Fix compilation error from device api

* [wasm] Apply device api changes

* [wasm] Format and cleanup

* [wasm32] Implement gamepad connections

* [wasm] Harmonize

* [Test] Made some tests with wasm-pack

* Quick fix instant non supporting Hash trait

* Fix on_received_character

* [web_sys] Split add_event and add_window_event

* [web] split device implementations

* Update tests/web...still does not work

* [tests/web] do not ignore index.html

* [web/web_sys] split canvas and window

* [tests/web] enable stack trace

* [web] fix borrowmut

* [web_sys] fix gamepad registration

* [web] harmonize naming

* [web_sys] create global emitter

* [web] implement gamepad buttons

* [web] implement gamepad axis

* [web] cleanup

* [web] update test

* [web] move tests/web to examples/web

* [web] axis does produce stick event

* [web] Support Stick event

* [web] implement gamepad to stdweb

* [web] rename examples/web to examples/wasm

* [web/web-sys] Move gamepad_manager from backend

* [web/web_sys] implement EventLoop::gamepads

* [web/web_sys] Drain gamepad events

* [web/stdweb] apply web_sys changes

* [web] update web/examples

* [web] move gamepads code to gamepad_manager

* [web] simplify and optimise

* [web] replace EventCode to GamepadAxis and GamepadButton structs

* [web] reuse gamepad events due to chrome issue

* [web] rumble does not work

* [web/stdweb] try debugging

* [web] fix Chrome gamepad not updated

* [web/stdweb] created an example

* [examples] fix paths

* fix warnings

* [web/examples] update comments

* [web/stdweb] add experimental support to vibrate()

* [web] add CR

examples/web/gamepad/websys/Cargo.toml

@@ -0,0 +1,20 @@
+[package]
+name = "websys-gamepad"
+version = "0.0.1"
+authors = ["The winit contributors", "Pierre Krieger <pierre.krieger1708@gmail.com>"]
+edition = "2018"
+
+[lib]
+crate-type = ["cdylib", "rlib"]
+
+[dependencies]
+winit = { path = "../../../../", features = [ "web-sys" ] }
+wasm-bindgen = "0.2.45"
+wasm-bindgen-test = "0.3.8"
+web-sys = { version = "0.3.22", features = [ "console" ] }
+
+# The `console_error_panic_hook` crate provides better debugging of panics by
+# logging them with `console.error`. This is great for development, but requires
+# all the `std::fmt` and `std::panicking` infrastructure, so isn't great for
+# code size when deploying.
+console_error_panic_hook = "0.1.6"