version 0.98 pre2: minor fixes and updates

version 0.98 pre2: minor fixes and updates

* at status bar left below ships are displayed for lives left
* armor bar is two pixels high (better visible)
# bullet overflow fixed again (>63 bullets fired)
# correct weapon loaded when continuing a saved game
# game froze when generating a random value <=1
* you explode in a different way than the enemies
+ screen inverts for a brief time when you are hit!
# stats-bar was messed up when ya got 0 lives left
* new (big) boss modeled after a common MSX Nemesis2-boss
* score increased once every 32 frames (instead of every 256)
# ground fixed for new random routine (smaller routine; incs -2 to 2)