Implementation of Wii extension output via I2C

[mikepparks]

Extension output mapping will use the same configuration in use for input. However, connectivity will require pulling the Sense/Detect pin HIGH on the Wii extension breakout in order for the controller to correctly detect a connection.

Caution

Currently, the Classic and Nunchuck modes are functional in homebrew and the retail Wii menu, but not fully tested in game situations. The remaining extension modes display quirky behavior (held button presses or analog directions) and requires further investigation before this can be considered complete.

Wii output encryption functionality based on work by @Santroller, @RobertDaleSmith, and marcan

To-do:

• Fix issue causing incorrect inputs to be sent in Output mode for non-Nunchuck/Classic controller types.
• Add a toggle between Input and Output modes to web config.
• Add Output Controller type to web config.
• Clean up debug output code.
• Fully implement Train controller input and output.
• Implement UDraw and Drawsome output.
• Fix issue with Input mode analogs sometimes appearing way outside of range when translated to 16 bit precision.