Change to use runtime system's "os2winp" support. Change

Change to use runtime system's "os2winp" support.  Change
corresponding to microcode which now supports multiple event queues
for windows.  Add subprocess support.  Reimplement management of state
so that windows are closed down properly when the editor is killed.
Change code that "controlifies" input characters -- previously it was
not doing this correctly.  Change handling of paint events to clear
the region being painted before drawing in it -- previously the
microcode took care of this, but it no longer does so.