Adding dynamic USB power support

- Each scan module now has a current change callback which passes the available current as a parameter
- No longer attempts to use the max 500 mA immediately, starts with 100 mA then goes to 500 mA after enumeration
- If enumeration fails due to bMaxPower of 500 mA, then attempt again at 100 mA (might also be possible to go even lower to 20 mA in certain cases)
- Now working with the Apple Ipad (no over-power messages)
- Fixed Wake-up behaviour on Apple Ipad (and likely other iOS devices)
- More effecient set_feature/clear_feature handling (device handler)
- Initial power handling via Interconnect (still needs work to get it more dynamic)

Scan/WhiteFox/scan_loop.c

@@ -1,4 +1,4 @@
-/* Copyright (C) 2014-2015 by Jacob Alexander
+/* Copyright (C) 2014-2016 by Jacob Alexander
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -97,3 +97,13 @@ inline void Scan_finishedWithOutput( uint8_t sentKeys )
 	Scan_scanCount = 0;
 }
 
+
+// Signal from the Output Module that the available current has changed
+// current - mA
+void Scan_currentChange( unsigned int current )
+{
+	// Indicate to all submodules current change
+	Matrix_currentChange( current );
+	LED_currentChange( current );
+}
+