copy qml files only once in debug-and-release builds

the condition is copied 1:1 from the BUNDLE_DATA logic in qt_module.prf.

Task-number: QTBUG-41267
Change-Id: Ia80a9a29319f70017e090855cf8d35a77b9e727f
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Fix cancel operation for example "Application"

On the save dialog the cancel option is detected now from exec()
method.

Change-Id: I977626b83fe770ddc148b57551becd04e5fd9dd5
Task-number: QTBUG-41020
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>
make it possible to suppress warnings of the vcxproj generator

When the user adds a compiler option that qmake doesn't understand, a
warning message is printed. One can suppress these warnings now by
adding CONFIG+=suppress_vcproj_warnings to the project file.

Task-number: QTBUG-37520
Change-Id: Ieb7ad2c900329e76636047dff85824ea0456f608
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Remove qtdemo from gitignore

QtDemo was removed with a commit in qtdoc.

Change-Id: I1803e041e7da57641148a37691ffdc6ae6c85ad9
Reviewed-by: Alessandro Portale <alessandro.portale@digia.com>