Added `mat2x3_transposed`

Closes https://github.com/PistonDevelopers/vecmath/issues/42
Added `mat3x2_transposed`

Closes https://github.com/PistonDevelopers/vecmath/issues/43
Added `mat4_col`

Closes https://github.com/PistonDevelopers/vecmath/issues/45
Added `mat4_transposed`

Closes https://github.com/PistonDevelopers/vecmath/issues/45
Merge pull request #46 from bvssvni/master

Added transposed functions