[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
[FEATURE] Python 3 support

- switch to absolute imports
- use print function
- replace cPickle
[FEATURE] Python 3 support

- switch from str to bytes in addons
[FEATURE] replace str with bytes in converters

- use now bytes in all custom converter classes
[TEST] switch from str to bytes in tests
[FIX,BUILD] fix build issue in pyOpenMS

fix Cython code that does not use const in a function which will take
arguments of type "const char *". Adding the const qualifier in the .cpp
file fixes this issue.

fixes #745
[TEST] fix collections and consumer
[TEST] fix integration and memory tests