Merge pull request #237 from bvssvni/master

Added `Texture` type
Merge pull request #239 from bvssvni/master

Made `Texture` RAII collected
Merge pull request #240 from bvssvni/master

Removed `AssetStore` from `Gl`
Merge pull request #242 from bvssvni/master

Added `from_path` constructor to `Texture`
Merge pull request #244 from bvssvni/master

Added `path` to `AssetStore`
Wrote about `AssetStore`
Update tutorial.md
Added how to generate docs with piston-workspace

Closes https://github.com/PistonDevelopers/piston/issues/246
Wrote how to load images

Closes https://github.com/PistonDevelopers/piston/issues/157
Merge pull request #252 from bvssvni/master

Upgrade to latest Rust
Merge pull request #253 from bvssvni/master

Upgraded to latest Rust
Removed outdated '.rlib' information

Closes https://github.com/PistonDevelopers/piston/issues/254
Fixed word order
Changed path method on AssetStore to take &self insted of &mut self
Merge pull request #258 from leonkunert/master

Changed `path` method on `AssetStore` to take `&self` insted of `&mut self`.
Removeds chapter `loading sounds` from tutorial

Closes #247
Merge pull request #259 from leonkunert/master

Removeds chapter `loading sounds` from tutorial
Add a preliminary AudioBackEnd which is able to play sound
Merge pull request #261 from bvssvni/master

Rewrote `Game` trait to use iterator
Merge pull request #263 from bvssvni/master

Using `Args` types in `Game` trait