Currently object handles are defined in the bitmap which is a pain
when using in HiDPI as they have to be scaled and don't look
pretty. They are also hard to change and non theme-able (change
of color needs a change the bitmap). This commit experimentaly
enables the drawn handles (enable with environment variable
SVX_DRAW_HANDLES) which currently exchanges the default some
basic handles.

Change-Id: If80aa7fe756a6d8d6991e9515f2951ee21b31b72