Remove viewport_paint_underground_setup, it's just gfx_clear
decompile window_map_scrollpaint()

Not sure if preserving the top g1_element is of any importance;
I haven't noticed anything breaking when I removed it.
Fix window_map_mouseup() (it was callling window_options_mouseup() instead)
Merge pull request #243 from adrian17/map_window

Decompile window_map_scrollpaint() and fix window_map_mouseup()
Merge pull request #242 from adrian17/viewport_cleanup

Remove viewport_paint_underground_setup, it's just gfx_clear