[INTERNAL,API] Removal of the GSL

Pull request to include the removal of all GSL code in OpenMS.


- GSL build modules are not removed so far

- GSL ist not removed from the contrib repos

- more than a few unit test needed adaption. this is due to the change in numerical calculations when changing libraries

- some unit test still fail:
Linux64: AccurateMassSearchEngine_test (file missing)
Linux32: AccurateMassSearchEngine_test, TOPP_OpenSwathWorkflow_1_out1 (numerical), TOPP_PeakPickerWavelet_3_out1 (numerical)
MacOS: AccurateMassSearchEngine_test,  TOPPView_test (X missing), TwoDOptimization_test (numerical)
Win64: AccurateMassSearchEngine_test
file missing - the test needs a file that was removed when the repos was split
X missing: no X installed on the test system
numerical: unit test see significant numerical differences in some calculations (this needs to be checked)

- note: not every state of the commit-history compiles. it should be possible to extract [BUILD, FIX] commits