Permit window resizing

[Mikolaj]

Honor minimal size --- the one we have currently that fits the whole HUD. One difficulty of this issue is technical, catching the resize event and redrawing correctly. Another is generalizing various UI-drawing code to cope with bottom line having a different number, etc. It's mostly hard-coded now and sometimes wrongly bound to dungeon level size instead of windows. Lastly, the improved code should really use the extra screen space, not just pad with spaces.

[Mikolaj]

To simplify things, let's stick to fixed window size per game (defined in game content) and let resizing only zoom the view by changing font scale. Then it reduces to #127. Closing in favour or #127.