[API,FEATURE,TEST] Improved fitting of models to mass traces

- new method "getValue" to evaluate the model at a point
- more robust estimation of initial parameters for Gaussian model (caveat: fitting may use more steps in some cases)
- adapted tests
[FEATURE,PARAM] added checks for elution model validity; changed settings of OpenSWATH feature finding
[INTERNAL,TEST] increased accuracy of approximation for AUC calculation (for consistency), adapted tests
[FEATURE] PeakFileOptions extension

- extend PeakFileOptions by an maximal_data_pool_size_ parameter which
  specifies how many spectra should be read before being processed
[FEATURE] parallel spectra processing for mzML

- while reading, the spectra are decoded in parallel which allows for
  faster read times of the mzML data format
[FEATURE] parallel spectra processing for mzXML

- while reading, the spectra are decoded in parallel which allows for
  faster read times of the mzXML data format.
fix some forward declarations
[FIX,TEST] fix typo, add test
[FIX] fixes suggested by Chris

- correctly handle update of shared variable
- move PeakType out of loops
[FEATURE] Add parsing of TPP modifications to AASequence

- parse modifications in TPP format:

- allow parsing of modified peptides in TPP/SpectraST format with
  integer (PEPT[181]IDE) or accurate (PEPT[181.004]IDE) masses
- allow parsing of modified peptides in TPP/SpectraST format with
  integer (PEPT[+80]IDE) or accurate (PEPT[+79.96632]IDE) mass
  differences
[FIX] fix TraML Reader code
[FIX] stop parsing upon error
[NOP] unified lineendings in OpenMSBuildSystem_configh.cmake
[INTERNAL] moved all path related config infos to a separate header

 * the header is only included by File.cpp to avoid unnecessary access
 * added some more comments and structure to OpenMSBuildSystem_configh.cmake
[INTERNAL,NOP] moved OpenMSBuildSystem_configh.cmake into src/openms
[INTERNAL] moved package types etc. to top-level CMakeLists.txt
[BUILD,INTERNAL] added additional search paths in the CMAKE_INSTALL_PREFIX

 * Note: Installation is completely disabled for now
[BUILD] reenabled install target for OpenMS(_GUI), OpenSwathAlgo, TOPP/UTILS

 * doc is now part of ALL to ensure that the documentation is ready when it is installed
[NOP] added xvfb to travis execution to allow gui related stuff

 * since doc is now part of ALL and doc needs a GUI we need travis to run with an X Server (xvfb)
[NOP] removed old, now obsolete installation cmake files