QmlDesigner.StatesEditor: Do not allow adding states to Window

We only checked for ApplicationWindow. Instead of ApplicationWindow
we have to check for Window. ApplicationWindow is derived from Window.

Change-Id: I5d287af4284e31dcd77e06b498c5ae61dc348ad6
Reviewed-by: Marco Bubke <marco.bubke@digia.com>
replace platform conditional with QMAKE_DIRLIST_SEP

Change-Id: I2646a2c30573417ba9da4b57b100d33144cef349
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>
Merge remote-tracking branch 'origin/3.1'