Added new constructors to Matrix

Added constructors that take only a Vec3, Vec4 or Array and then sets
that as a column vector for the new matrix.
Also cleaned up redundant parameters to other constructors.
Added an isSquare method.
Fixed the bug caused by missing 2 negative signs.

It works now!
Added toString() method for Vec4
Revamped LUDecomposer

The decompose method now returns an array of matrices instead of
mystical "result" objects.
Created new exception for matrix class
Worked more on the model center calculator.

Added a 'calculateDeterminant' method for the rotation matrix. It works!