This handles good breakdown in bicgstab(ell)

The breakdown may occur if solution obtained on a previous iteration of
Bi-CG part of bicgstab(ell) is exact. This may happen if amg hierarchy
consists of a single level (that is, the problem is too small).
Merge pull request #8 from ddemidov/bicgstabl_breakdown

This handles good breakdown in bicgstab(ell)