This is a regression from c1b9adb691 and (my commit) 287c23f126.
It is not safe to remove opcodes from proc.stmts since labels
are sometimes referenced by their offset in the list. So, instead
they are now replaced by op._nop.
This fixes kLoadingorsave not being set in doload(), which was
visible when going to the load game menu from the startup menu.
This gets rid of some unused labels. We need to be careful
not be optimize too much, as that could remove the very label
the unbounded block was added for.
Eugene Sandulenko
Willem Jan Palenstijn
Vladimir Menshakov