Make better use of implicit conversions.
Made Vector::Normalize return the length of the vector before normalization.
Fixed typo.
Added Matrix constructors that take Vectors and Normalize methods.
Added decomposition functions to the matrices and got rid of the construction functions (to be reimplemented as constructors).
Separated Vector constructors into separate file.
Moved around some includes.
Added EulerAngles class and added conversion constructors between EulerAngles and Matrix.