[FIX] Bugfix for threading issue in MascotGenericFile

- Fixes an error introduced by multiple threads: under certain
  conditions the global variable has_next could already be set to false
  before it is checked by a thread that still has work to do on a last
  spectrum. In this case the last spectra would not get added to the
  MSExperiment container.

Fixes #683
Merge pull request #685 from cbielow/develop

Typo fixes in documentation and licence files
[FIX,PYOPENMS] fix pyOpenMS after #680

- also adopt header files and changed API in pyOpenMS code
[FIX] catch error in seekg

- catch error when seekg cannot go to the requested position and
  re-throw a sensible error message
[FIX] use std::streampos in CachedMzML (multiple fixes)

- use std::streampos to store positions in filestreams
- check for error condition before resize on untrusted input in
  readSpectrumFast / readChromatogramFast
- fix handling of positions received from tellg, instead use combination
  of seekg and ifstream::cur
[TEST] adapt test for CachedMzML
[FIX] use std::streampos in IndexedMzML

- use std::streampos which allows to address also larger files
[FIX] correctly read file position from XML into std::streampos
[TEST] add test
[FIX] properly release xercesc resources after use
Merge pull request #684 from hroest/fix/MascotGenericFile

[FIX] Bugfix for threading issue in MascotGenericFile
[FIX] fix build for MSDataCachedConsumer_test after API change
Merge pull request #688 from hroest/fix/FileSizeLimit

Fix/file size limit