[FIX] Fixing assertion in graph_algorithm_refine_inexact.h.

As reported and fixed by Birte Kehr.

Also see http://trac.seqan.de/ticket/1128
[FIX] Fixing a bug in removeGaps() for gaps_array.h.

Reported and fixed by Birte Kehr.
Merge pull request #130 from holtgrewe/hotfix/refinement_bugs

Hotfix with refinement and gaps bug.