Sometimes it is not necessary to include the whole Cutter.h file
Hence, it's been splitted so you can include only what you require
E.g. #include "core/CutterCommon.h" to have access to the common types
* Improved xref widget performances
Removed call to afij that could be very slow.
* Deleted destructor definition
It is bydefault defined in QObject derived
classes so since it's empty we should better ommit it
* Use pd-- and readd destructor