AmiSC 68K v0.7.6

The big one in this release is speed. A crowded late game on a 68020 spent
62 ms of logic on every 42 ms tick, which is why it crawled. There is now a
LOGIC row in the start menu with three settings, and on a saved position with
374 units and four computer players, measured on a 68020 with no JIT:

LOGIC	what it means	logic per tick
NORMAL	every unit thinks every tick, exactly as the original	63.4 ms
FAST	every unit thinks every second tick	47.7 ms (-25%)
FASTEST	every unit thinks every fourth tick	35.4 ms (-44%)

What FAST and FASTEST do NOT change: rate of fire, shield and health
regeneration, energy, build times, how long a spell lasts or how long a burning
building survives. All of those keep their speed - the call that does happen
counts the ticks that were skipped. What changes is reaction time: a unit
answers an event up to one tick later on FAST and up to three on FASTEST. Units
already walking a route keep walking it every tick, so nothing moves in jerks.

NORMAL is the default and is bit-for-bit the original.

• Computer versus computer. A row in the start menu fills every slot the map
  offers with a computer player and leaves you watching. Fog is forced off for a
  watcher, otherwise the screen would be black.
• Save and load. SAVE GAME in the in-game menu (F10), or F5 while playing.
  LOAD SAVED GAME is in the START menu, under START GAME - pick the map the
  position was saved on, then load it. Loading into a match already in progress
  is still not offered; it is not ready.
• The start menu scrolls. It outgrew the screen, so there is a scroll bar on
  the right with two arrows and a draggable slider. The rows no longer shrink to
  fit, which used to make every old row worse each time a new one was added.
• Smaller buttons in the file selector. They were a fixed width, and four of
  them did not fit a 320-pixel screen - they overlapped. Each is now as wide as
  its own label.
• Smoother 320x240 graphics (from v0.7.3, not released until now). The filter
  covers the whole inside of every unit and building rather than only the parts
  away from the outline, and the terrain is filtered once per terrain type and
  kept in data/lores-<terrain>.pack, so later starts only read it. If you
  converted with v0.7.0-0.7.2 the game asks once whether to convert again;
  "keep as is" is remembered in settings.cfg as smooth_lores_gfx 0.
• Fog of war costs less on every setting, including NORMAL. A unit that has
  not moved off its tile no longer recomputes what it can see - the same bits,
  computed once.

Known, and not fixed in this release: if you change the video mode while the
menu is open, the emulator or monitor may keep the old size for the rest of that
session and show the smaller screen in a corner. Starting again picks the
remembered mode straight away and looks right. One race's buildings, and a
handful of units of the other two, are scaled with the wrong filter in the
320x240 modes; the cause is known and the fix is not in yet.