Update space dispatch:

- drawXXXspace, changeXXXspace, and winqreadXXXspace now receive the area
     and spacedata as explicit arguments, allowing them to access private
     data w/o going through globals.
 - pass the new BWinEvent through to the winqreadXXXspace, allowing future
     access to extended event data.

Removed direct calls to winqreadXXXspace to simulate user actions, replaced
by calls to action functions in edit.c or the appropriate handler.

source/blender/include/BSE_editipo.h

@@ -81,6 +81,7 @@ void test_editipo(void);
 void get_status_editipo(void);
 void update_editipo_flags(void);
 void set_editflag_editipo(void);
+void ipo_toggle_showkey(void);
 void swap_selectall_editipo(void);
 void swap_visible_editipo(void);
 void deselectall_editipo(void);