[INTERNAL] Splitting test for seeds module.

This hopefully lowers compilation memory requirements for Travis builds.
Merge pull request #246 from holtgrewe/feature/split_seed_tests

[INTERNAL] Splitting test for seeds module.
Merge branch 'develop' into feature/seqanLast
prepare benchmark_SACA for runtime tests
Merge branch 'feature/seqanLast' into bugfix/fixRadixSort
runtime tests for radix sort on random texts
fixed type of ValueSize according to issue #256 in seqan/seqan