qmltc: generate handlers for signals defined in c++

Qmltc has troubles connecting handlers to its corresponding signals defined in C++ (while the engine does it without problems).

You can find an example in the attached problem (look for main.qml for the onXXX-handlers). It runs fine without type compilation but fails to compile qmltc's generated code when using ENABLE_TYPE_COMPILER. I believe it should either run or print a message that some cases are unsuited for type compilation.