[PYOPENMS] changed extra methods on MSSpectrum

    get_peaks and set_peaks now return and receive different
    precisions for mz and ii, so that we get better resolution for mz.
    mz was float32 and is now float64
Merge pull request #754 from uweschmitt/feature/pyopenms_float64_for_peaks

[PYOPENMS] changed extra methods on MSSpectrum
[FIX] replaced DoubleReal and Real by double and float
[FIX] allow empty RT input

- OpenSwathWorkflow allows to not specify an iRT input file (it will
  simply assume that no iRT correction is requested and print a warning)
[FIX] move computation of overlapping features

- perform computation of overlapping features _after_ the boundaries are
  re-computed
[DEBUG] add option to get irt chromatograms for debugging
[FIX] pyOpenMS changes
[fix] replaced DoubleReal and Real in pxd files
[BUILD] fixed macosx extra libs (reduced to subset, CoreServices, CoreFoundation, OpenGL)
[BUILD,PYOPENMS] removed offending link args
[BUILD,PYOPENMS] fixed some more pyopenms compile issues on mac osx
[BUILD,PYOPENMS] made pyopenms.cmake a bit more cmake like
Merge pull request #784 from aiche/feature/fix-macosx-pyopenms-errors

[FEATURE] fix macosx pyopenms errors
Merge pull request #779 from timosachsenberg/feature/DoubleRealRemoval

[FIX] replaced DoubleReal and Real by double and float.
Merge pull request #781 from hroest/fix/OpenSwathFixes

Fix/open swath fixes
Merge branch 'develop' of https://github.com/OpenMS/OpenMS into fix-idpep-mascot