data: ClangTool gets invoked for cpp files only, headers are parsed on-the-fly

This change adds the class FileRegister, that splits cpp and h files for the Parser and keeps track which headers have
been parsed yet. TranslationUnits get only created for cpp files now, and headers are parsed on the fly. This reduces
parse time by around half.

src/lib/data/parser/cxx/ASTActionFactory.cpp

@@ -1,8 +1,8 @@
 #include "data/parser/cxx/ASTActionFactory.h"
 
-ASTActionFactory::ASTActionFactory(ParserClient* client, FileManager* fileManager)
+ASTActionFactory::ASTActionFactory(ParserClient* client, FileRegister* fileRegister)
 	: m_client(client)
-	, m_fileManager(fileManager)
+	, m_fileRegister(fileRegister)
 {
 }
 
@@ -12,5 +12,5 @@ ASTActionFactory::~ASTActionFactory()
 
 clang::FrontendAction* ASTActionFactory::create()
 {
-	return new ASTAction(m_client, m_fileManager);
+	return new ASTAction(m_client, m_fileRegister);
 }