Added `get_size`, `get_width` and `get_height` to `Texture`
Added `get_size`, `get_width` and `get_height` to `Texture`

Closes https://github.com/PistonDevelopers/gfx_texture/issues/7

PistonDevelopers/gfx_texture,mitchmindtree/gfx_texture,bvssvni/gfx_texture