Fix 4x4 rotation constructors and 4x4 * vec3
Fix 4x4 rotation constructors and 4x4 * vec3

4x4 matrix rotation constructors didn't initialize col3.w to 1.0.

4x4 * vec3 didn't work because of a missing check in operator*.

Signed-off-by: John McCutchan <a51dda7c7ff50b61eaea0444371f4a6a9301e501@johnmccutchan.com>

brason/vector_math,julien/vector_math.dart,brason/vector_math,julien/vector_math.dart