Fixed bug with Slerp and RotationOrientationInverse

negate warp around quaternion instead of invert inside Slerp, invert
after finding rotation-orientation in RotationOrientationInverse, all
tests pass, no SSE in Quaternion yet
Added some SSE

added some SSE to Quaternion, added a couple new SSE methods, added
tests for new stuff, cleaned up tests and made them more uniform, all
tests pass
Finished first pass at Quaternion SSE

added SSE to most Quaternion methods, replaced many divide-by-zero
if-checks with asserts, refactored tests so they make more sense, added
some comments to the tests to break each method into descriptive
sections, added missing gitignore