Fixed drawing order of tiles on the fringe layer

Now they correctly interleave with the entities rather than always being
drawn below them.

To achieve this, they each get their own QQuickItem (a TileItem) so that
the right z value can be set on them. The items are only created for
actually visible fringe tiles. For a large number of fringe tiles this
could be further optimized by having only an item for each row.
Added a confirmation dialog to character deletion
QtQuick2ApplicationViewer updated by Qt Creator
Micro-optimization in joystick

Like this it avoids executing joystickPosition() twice whenever any of
its dependencies change.
Removed a bunch of unnecessary unload() calls

The AbilityDB, HairDB, NpcDB and RaceDB do not need to do a manual
unloading upon destruction, because the objects that they manage are
their children and as such will already be automatically cleaned up.

MonsterDB was failing to clean up its MonsterInfo instances entirely,
though when some would be returned from getInfo to the QmlEngine, it
would have taken ownership of them since they didn't have any owner (but
this currently never happens).

Actually I was trying to fix a crash on exit with Qt 5.1.1, but this is
still there. Fortunately, it seems to be more a problem in Qt which has
been fixed in Qt 5.2 beta1.
Added reading of attribute and correction points