Added slice moves, double moves and cube rotations. Added package rubiks-alg.

[Hultan]

Added the following functions to package rubik:

• Slice moves (M, Mc, E, Ec, S, Sc).
• Double moves (Ud, Udc, Dd, Ddc, Rd, Rdc, Ld, Ldc, Fd, Fdc, Bd, Bdc).
• Cube rotations (X, Xc, Y, Yc, Z, Zc).

Added the package rubik-alg:

• ExecuteAlg function, execute an alg (string) and returns a new cube.
• ReverseAlg function, reverses the provided alg, ex "x F U' L" becomes "L' U F' x'".
• GetScrambledCube function, returns a scrambled cube and the scramble alg.