Changelog for 3.0-176

Merge branch 'gc-mic'

Added GameCube Microphone support.  Uses your default audio recording device.  The Microphone is selectable from the Slot A/Slot B pulldowns under the GameCube tab.  The Microphone button can be set under GCPad configuration for pad 1 and 2. Thanks to MooglyGuy and skidau.