Fix Key_StringToKeynum to return lowercased ascii

Fixes bind and unbind uppercase ascii and uppercase ascii in cl_consoleKeys.

keycodes.h states "normal keys should be passed as lowercased ascii"

code/client/cl_keys.c

@@ -800,7 +800,7 @@ int Key_StringToKeynum( char *str ) {
 		return -1;
 	}
 	if ( !str[1] ) {
-		return str[0];
+		return tolower( str[0] );
 	}
 
 	// check for hex code