Make qbs-config-ui menu more cross platform.

Use QKeySequence for cross-platform shortcuts,
and set the menu role for the Exit/Quit item.

Change-Id: I8143f562efdba1cb315c4e4762baf3472165122a
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Christian Kandeler <christian.kandeler@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
libqtprofilesetup: Gather information about Qt plugins.

And create modules for them. These also handle the creation
of the "import" source file when building against a static Qt.

Change-Id: I883a1dd96c5e38c9d4bb5c13af807b1bf388f8b1
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>