Changeset c394de8 for editwin.c

Use ref-counting to make editwin ownership saner

When creating an editwin, one creates an editcontext which takes a
reference to the editwin. Likewise, the pointer in owl_global holds
reference. The reference counting manages their ownership claims. In
addition, owl_global_set_typwin_inactive now does release a reference.

Instead, the callback-calling commands take a reference and release it
later. We may wish to further improve that so that the contexts are also
ref-counted such that, when their commands are running, they will not be
deallocated, even if popped. That will avoid the callback dance.