Contrary to what the name would have you believe, QPointer<> is not used
to delete a pointer when it leaves its specific scope. Instead, it's
used to check to see if the pointer is still valid. For most
QWidget-based objects, this is actually fine because QWidgets that are
assigned to layouts or other widgets will automatically be destroyed --
however, for non-widget objects, this can cause a memory leak.
This patch replaces QPointer with QScopedPointer where applicable to
prevent memory leaks.
Closesobsproject/obs-studio#1367
The OBSBasicFilters window did not register a handler for the
"update_properties" signal. Now it does. Addresses issue #1028.
Closesjp9000/obs-studio#1036
In the filters dialog, when the properties are being updated due to
filters being added/removed/switched, using deleteLater on the previous
view would cause it to linger in the view until the deleteLater is
processed by the Qt queue, displaying two views instead of one.
Additionally because of that, this would also cause the display in the
filters dialog to resize as well, causing the reorder mutex hard lock
which was fixed by the parent commit.
Closesjp9000/obs-studio#714
