Some more tweaks to cursor handling

- Fix cursor turning into a sword during universe shifts
- Hide cursor along with menubar during splash screen
- Add watch cursor, used during splash screen
- Properly restore cursor after a dialog
- Use sword cursor for dialogs
- Show ibeam cursor in dialog text fields
- Move everything cursor-related out of graphtool

osx/pcedit/pc.main.cpp

@@ -15,6 +15,7 @@
 #include "fileio.h"
 #include "pc.menus.h"
 #include "winutil.h"
+#include "cursors.h"
 #ifdef __APPLE__
 #include <CoreFoundation/CFByteOrder.h>
 #endif