Generalized Ray & Transform over dimensions
Rotation is generalized over dimensions
Generalized transform trait over any-dimensional vectors and points
Homogeneous transformations added for Point3; extend/truncate added for vectors; Transform3 is implemented for AffineMatrix3
Fixed tests to compile; added Point homogeneous transform & test; added Transform inversion & test; Implemented Transform for AffineMatrix3
Merge branch 'master' of https://github.com/kvark/cgmath-rs into kvark-master

Conflicts:
	src/tests/plane.rs
	src/tests/vector.rs