This enables two of the "unfinished" puzzles. Slide requires a new "sticky
mouse mode" to enable dragging. The help system is disabled for these
puzzles, since they lack manual chapters.
Group is currently unplayable due to lack of request_keys() support, which
will need to be added upstream. Separate fails to draw anything.
Change-Id: I7bcff3679ac5b10b0f39c5eaa19a36b4b1fe8d53
