Revert "remove invalid/duplicate setuid from main from #128", because it makes DT not run on Mac.

This reverts commit ab18ba31de0c68827d52b996dadfdea306e38887.

Conflicts:
	src/main.cpp
Fixed copying memory_layouts in project file
Q_OS_MAC for setSetuidAllowed

cizra's merge fixes #190 (osx layouts)  and fixes #191 (permission
crash)

the call to setSetuidAllowed is explicitly required for osx, but won't
compile on other platforms. for now the Q_OS_MAC check should suffice
until someone with a mac can debug why the setSetuidAllowed called in
dfinstanceosx authorize isn't sufficient.

the docs also say this should only be necessary in qt version >= 5.3
which should also be tested
fix more clang warnings