Added a spectral test for the pressure operators H and Hhat.

Calculate matrix representation of H and Hhat and check that the condition number of Hhat^{-1}H is smaller than 2 (this numerical value is a bit random, so maybe relax it to 10).
Added correct lapack libraries for banded matrix kernels.

With the recent change to PyOP2, the libraries which are linked to for a particular kernel are now specified as arguments when constructing the kernel.
Added banded matrix transpose

New function for calculating the transpose of a banded matrix.
Bugfix: incorrect loop bound

The upper second loop bound in the matrix transposition kernel has to be set to the number of columns of the matrix which is transposed, not the number of columns of the resulting matrix.
Removed incorrect and misleading comment.
Convert matrix to dense format.

Added method for returning the banded matrix in a dense storage format, i.e. in each column the banded matrix is represented by a n_row x n_col matrix. This method might be useful for debugging.