* Show list name in software selection menu (machines have multiple
lists).
* Actually report software list parsing errors during validation.
* Check that software list name attribute matches filename.
* Limit software list names to 24 characters - they're getting too long,
and they need to be practical in command lines.
* c128.cpp: Fix dangling reference to renamed software list.
-emu/ioport.cpp: Slightly better test for deselected slot cards.