Removed occurences of copy/Copy + improved api.

Now, access to vector components are x, y, z, w, a, b, ... instead of at[i].
The method at(i) has the same (read only) effect as the old at[i].

Now, access to matrix components are m11, m12, ... instead of mij[offset(i, j)]...
The method at((i, j)) has the same effect as the old mij[offset(i, j)].

Automatic implementation of all traits the compiler supports has been added on the #[deriving]
clause for both matrices and vectors.