Fixes:
src/gui/CloneDialog.cpp:32:5: error: use of undeclared identifier 'setWindowFlag'
setWindowFlag(Qt::WindowContextHelpButtonHint, false);
^
void QWidget::setWindowFlag(Qt::WindowType flag, bool on = true)
--> This function was introduced in Qt 5.9.
* Remove Git revision finding code in favor of a simple command call: git rev-parse --short=7 HEAD
* Added GIT_HEAD_OVERRIDE to explicitly define the hash for the current commit in case git is not available
* Made WIX default over NSIS in release tool
* Rename version.h to git-info.h