fiddling

preparing stuff to implement "facing". Starting from the need of working
mouse support and handling of UI.

- quote splash screen can now be skipped by pressing a key OR a mouse
button
- added an image blitted to a "border" console to draw on root when
screen space goes off the map area
- reworked some offsets so that the blit is always in range (not in bigg
mode)
- some mouse prompts/debug currently always on

TO DO
- use separate consoles for big and small tiles and only draw the
relevant portion of the map. Right now: all the map is built, but only
the visible portion is blitted.