Support these new cards in slots 3, 4 or 5; based on code from Lukazi.
- extend Configuration's Input prop sheet page.
- add save/load snapshot for both cards.
- add command line switch for alt controller type (for SNES MAX card).
Change to using Registry's 'Configuration\Slot 3' for slot 3 cards (Uthernet, 4Play & SNES MAX).
Update help doc.
Change to using Registry's 'Configuration\Slot n' for disk ii image pathnames (was 'Preferences').
Delete Registry's 'Configuration\Slot n' section each time there's a change of card.
Add same functionality to conf.ini.
LoadConfiguration(): load from the new Slot-n section (or otherwise the old legacy key).
Only update Registry's 'Starting Directory' for s6,d1.
Update help doc.
. Added a new Debugger Screen Layout html page (to describe soft-switch status) (Fixes#406)
- added a PPT doc which was used to generate the annotated screen layout image
. Added a note about Shift+LMB for toggling 6502 status flags (#483)
