NumLock becomes Hyphen. P2 gains Back Button.

This should alleviate some issues.

Docs/Changelog_sm5.txt

@@ -10,6 +10,10 @@ StepMania 5.0 Preview 2 | 20110???
 
 2011/06/13
 ----------
+* [InputMapper] Modify default mappings. Use the Hyphen key instead of the
+  Numlock key for Player 2's GAME_BUTTON_BACK. This should address some
+  issues with Player 2 being unable to back out if they use a laptop.
+  [Wolfman2000]
 * [NoteDisplay] Add two new metrics.
  * DrawRollHeadForTapsOnSameRow: bool, similar to DrawHoldHeadForTapsOnSameRow
  * TapHoldRollOnRowMeansHold: bool, true means hold and false means roll

src/InputMapper.cpp

@@ -64,7 +64,7 @@ static const AutoMappings g_DefaultKeyMappings = AutoMappings(
 	AutoMappingEntry( 0, KEY_KP_C2,	GAME_BUTTON_MENUDOWN,	true ),
 	AutoMappingEntry( 0, KEY_KP_ENTER,	GAME_BUTTON_START,	true ),
 	AutoMappingEntry( 0, KEY_KP_C0,	GAME_BUTTON_SELECT,	true ),
-	AutoMappingEntry( 0, KEY_NUMLOCK,	GAME_BUTTON_BACK,	true ),
+	AutoMappingEntry( 0, KEY_HYPHEN,	GAME_BUTTON_BACK,	true ), // laptop keyboards.
 	AutoMappingEntry( 0, KEY_F1,	GAME_BUTTON_COIN,	false ),
 	AutoMappingEntry( 0, KEY_SCRLLOCK,	GAME_BUTTON_OPERATOR,	false )
 );