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.
* Make Uthernet settings behave like all other cards.
Fix as well the fact that the Uthernet interface would not be reapplied after a restart.
* Uthernet: use consistent types to reduce code complexity.
Use std::string everywhere.
