Implement InputHandler for mouse movement

Project module (Configuration rework)

+ Adds a crate "amethyst-assets"
+ Example usage and README.md

This commit contains the core functionality
for asset management. This means that e.g.
formats or special syntax are to be done.

* Add input rebinding

* Correct lots of typos.

* Rewrite axis_value to be cleaner.

* Add _released functions to compliment _down functions.

* Remove outdated inline comment

* Rename functions to be less confusing.

* Add missing doc comments

Fix input in pong example

* specs v0.9 compiled

* examples on specs v.0.9

* docs on specs v0.9

* Remove adding default system . Add  to . Fix formatting and commenting issues

* Sort imports. Remove unncesessary

* TransformSystem is not thread-local. Sorting stuff

* Add direct access to World

Expose InputHandler types

Lifetimes for Application and Exposing InputHandler types

This commit renames asset_loaded to cache
and cached to retrieve.

* Update readme

Add language to indicate we don't officially support nightly or beta branches of Rust.

* Update README.md

* Update CONTRIBUTING.md

* Change language to be a bit less harsh.

* Move config back into its original crate so it can be used outside of amethyst

* Fix up documentation and examples for newer macro

* Travis develop branch specifier, alphabetical order for subcrates

Core asset management

Run rustfmt

Work around AppVeyor SSL problems

Input rebinding phase 2

This changes these functions to methods because they
essentially operate on the context.

* Integrate RON

* Fix compile error with serde default

* Add missing serde crate

* Fix examples

* Update documentation references to YAML

* Add entry to changelog

Add `Context` trait and move `Asset` functions to `Context`

…`Context`

A little tweak in amethyst_assets public interface

* Asset Hot Reloading [1/2]

* Add docs for type param A

* Optimize atomic operations

Split out implementation into multiple files
Add serde remote derive for VirtualKeyCode and MouseButton
Add Bindings structure which can be saved and loaded with amethyst_config
Restructure button/key/mouse_button API to use ButtonState to query for inputs in a specific state rather than having a function for each state.
Upgrade smallvec dependency to permit serialization and deserialization.
Fix pong example.

Remove broadcaster

… to draw method

…ependency, minor refactor

Add several static methods to Rgba

Allow color::Rgba to be used in constant buffers

Rename encoder.rs to enc.rs, update Encoder type

Allow light types to be uploaded as constant buffers

Add &Scene to PostprocFn, add LightIter and MeshIter to Scene type

Derive Serialize, Deserialize for TextureBuilder

…ods, test runtime PSO

…ods, test runtime PSO

…, basic Event and EventsIter code

…state.rs tests

…uilder::build() methods