* adjusted some help texts
* moved exclude paths and source file extensions contents to indexed paths selection in project setup wizard
* removed compiler flags from CDB project setup wizard
* added wizard content that shows some info text regarding the purpose of source groups
* renamed ContentSummary to ContentGroup
* fixed issue with CompilationDatabase include path extraction
* use canonical filepath cache in cxx indexer
* made constructors of FilePath explicit
* use FilePath at more places instead of string
* forward declares FilePath wherever possible