Add convenience init function to CGVector
Simplify lerp in CGVector
Add scalar addition and subtraction to CGVector
Update unit tests for CGVector
Fix Vector3 members not publicly accessible
Add init functions for Vector3
Add convenience dot/cross methods for Vector3
Add lerp and element-wise operations to Vector3

Supports +, -, *, /, along with assignment variants
Cleanup Vector3

-Remove .equalToScalar() in favor of equality operators
-Remove use of right: operator on dot/cross product functions
Add unit tests for Vector 3