Merge pull request #166 from bvssvni/master

Added `vec2_cast`
Merge pull request #168 from bvssvni/master

Added `vec3_cast`
Merge pull request #170 from bvssvni/master

Added `vec4_cast`
Merge pull request #172 from bvssvni/master

Added `mat2x3_cast`
Merge pull request #174 from bvssvni/master

Add `mat3x2_cast`
Merge pull request #176 from bvssvni/master

Added `mat3_cast`
Merge pull request #178 from bvssvni/master

Added `mat3x4_cast`
Merge pull request #180 from bvssvni/master

Added `mat4x3_cast`
Merge pull request #182 from bvssvni/master

Added `mat4_cast`
Merge pull request #183 from bvssvni/master

Added `vec2_mul`
Merge pull request #184 from bvssvni/master

Added `vec3_mul`
Merge pull request #185 from bvssvni/master

Added `vec4_mul`
Merge pull request #190 from bvssvni/master

Added `vec2_mul_scalar`
Merge pull request #191 from bvssvni/master

Added `vec3_mul_scalar`
Merge pull request #192 from bvssvni/master

Added `vec4_mul_scalar`
Merge pull request #194 from bvssvni/master

Made cast function unwrap internally
Merge pull request #196 from bvssvni/master

Fixed bug in `vec2_cross`
Merge pull request #198 from bvssvni/master

Removed duplicate code
Remove conversion functions replaced by cast

Closes https://github.com/PistonDevelopers/vecmath/issues/199