Override hashCode and equals.
Revert "Override hashCode and equals."

This reverts commit a257f2dfa0e2ef89ff8d522175d5d56b299a612a.
Override hashCode and equals.
Renamed method to operatorNegative.
Add toString() methods. Fixed getRotationAngleAxis to take a float array as a parameter.
Add missing methods.
Added unit tests for the mathematics package. All tests are passing.