[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
[TEST] updated test to reflect changes in GaussTraceFitter class
[INTERNAL] small simplification
[FIX] fixed checker warning (coding conventions)
[INTERNAL] added computeIntensityProfile() method to FFCentroided MassTraces

 * moved some code from header to source files
 * is faster then the previous map implementation currently used TraceFitters
[INTERNAL] utilize computeIntensityProfile in EGH- and GaussTraceFitter
Merge pull request #1 from aiche/hendrik/FFId

Improved intensity profile computation
Merge pull request #698 from hendrikweisser/FFId

[API,FEATURE,INTERNAL,TEST] updates to FeatureFinderIdentification and the TraceFitter classes