Vertex Loading

Added the ability to load vertex data from the WAD. Still needs
some processing to make more robust, but for now is loading data.

src/utils/mod.rs

@@ -2,5 +2,6 @@ mod error;
 mod helpers;
 
 pub use helpers::read_ascii;
+pub use helpers::read_i16_le;
 pub use helpers::read_u32_le;
 pub use helpers::validate_wad;