Fully support the mouse_support option for curses, via 'O' as well as
via config file. At the moment, mouse_support:1 and mouse_support:2
are equivalent.
Also, fix the screen-to-map coordinate translation. When the mouse
is active and over the map, the pointer's cursor becomes a cross-hair
(may very by platform) and the character cell chosen for a click
seems to be a few pixels to the right of the center of the '+'.
80374d46b5