Add controller options for Mouse in port 2 and Mouse in both ports

[InfiniteBlueGX]

This adds new controller configuration options for the SNES Mouse. The controller selection screen now features:

• "SNES Mouse (Port 1)" - this is the renamed "SNES Mouse" configuration that originally existed in Snes9xGX. Mouse in port 1, gamepad in port 2. Most Mouse games use this configuration.
• "SNES Mouse (Port 2)" - a newly added option where the Mouse is in port 2, and a gamepad in port 1. Certain games and romhacks like Wolfenstein 3D and Jurassic Park use the Mouse in port 2 exclusively, while simultaneously having gamepad functionality on port 1.
• "SNES Mouse (Both Ports)" - another new option where the Mouse is added to both ports. This allows games that support simultaneous Mouse inputs like T2: The Arcade Game and Revolution X to function with them. Mouse games that exclusively use port 1 or 2 will still have Mouse functionality under this configuration, but gamepad support on the non-mouse port will obviously not be available.

[dborth]

Sounds reasonable, thanks!