Added snake game sample (#111)

* Added snake game sample

* Worked on snake game sample:
- integrated with the other examples in the Cargo.toml
- removed the comment about cargo.toml, including unnecessary cmake dependency
- removed unused imports and functions, and unused impls
- swapped out rl/thd parameters for a rl.draw(&mut thd)
- removed commented out code
- removed unnecessary generics
- renamed add_direction to move_direction
- added win state to replace panic
- fixed bug for food sometimes placed out of bounds
- fixed spelling errors

Author: largenumberhere

samples/Cargo.toml

@@ -107,3 +107,7 @@ required-features = ["imgui"]
 name = "music_effects"
 path = "music_effects.rs"
 required-features = ["ringbuf"]
+
+[[bin]]
+name = "snake"
+path = "snake.rs"