data: parse typedefs

- added callbacks that will be called when clang encounters typedefs.
- added tests for this feature.

review id = 20

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src/lib/data/parser/cxx/ASTVisitor.h

@@ -22,6 +22,7 @@ public:
 	// 	return false;
 	// }
 
+	virtual bool VisitTypedefDecl(const clang::TypedefDecl* declaration); // typedefs
 	virtual bool VisitCXXRecordDecl(clang::CXXRecordDecl* declaration); // classes and structs
 	virtual bool VisitVarDecl(clang::VarDecl* declaration); // global variables and static fields
 	virtual bool VisitFieldDecl(clang::FieldDecl* declaration); // fields