Added crouch toggle, global bool called isCrouch, function agent_toggle_down bound to toggle_down.

Shift+crouch=toggle, crouch doesn't work while toggle crouched, at the moment.
Formatted keys.ini to be completely aligned.

indra/newview/llagent.cpp

@@ -69,6 +69,7 @@
 #include "llviewercontrol.h"
 #include "llviewerdisplay.h"
 #include "llviewerjoystick.h"
+#include "llviewerkeyboard.h" //For crouch toggle
 #include "llviewermediafocus.h"
 #include "llviewermenu.h"
 #include "llviewerobjectlist.h"