* Always add compiler header path when prefilling on first start, regardless of successful detection
* Show compiler header path in path list box on top and readonly
* Prepend compiler header path on Windows in system header path compiler flags, append otherwise
* Show warning when saving ApplicationSettings if compiler header path is not in global include paths
* Show warning when saving ApplicationSettings if there is another path containing compiler headers
* removed paths in include directives
* changed cmake to provide necessary header search paths
* changed name of version.h to productVersion.h due to name conflict
* added clang system headers to data folder of Sourcetrail repo
* added clang system header search directory to detected directories on windows
* updated migration to add clang system header search directory on windows
* updated windows installer and portable package to include compiler headers
* updated linux package
* cleaned code of path detectors
* unrelated removal of unnecessary code in LicenseChecker and UpdateChecker
* replace path to local compiler headers with packaged ones in include path detection
* added app settings migration to replace local compiler header path with path to packaged headers
Eberhard Graether