[API] Moving Fragment class to align module.
Merge branch 'develop' of github.com:seqan/seqan into feature/move-fragment-to-align
Merge branch 'develop' of https://github.com/holtgrewe/seqan into feature/move-fragment-to-align
Merge pull request #572 from holtgrewe/feature/move-fragment-to-align

[API] Moving Fragment class to align module.