version 0.8: pickups, enemy improvements, invulnerability

version 0.8: pickups, enemy improvements, invulnerability

+ contrast is increased one level at startup (and restored on exit)
+ invulnerable for a sec when you enter the game (inv-pickup later)
+ when in invulnerable-mode, your ship look different!
+ at the beginning you get three *hitpoints* so you can be hit 3 times
* bottomline icons are now 16 pixels wide and 7 pixels high!
+ hitpoint icon added: displays nr. of hps left next to a nice picture
* maximum invulnerability-time increased (can last upto 1024 frames)
+ when invulnerable-mode has nearly expired, your ship flashes!
* again a lot of optimizations esp. in size ('bout 100 bytes)
+ pickups! 10% chance a destroyed enemy changes into an armor-pickup
# code optimization caused some bullets to reappear as "fake" bullets
* pickups can't be destroyed by bullets (they pass right through it)
^ version 0.7
+ enemies move individually, not all at the same time! Looks very nice
# titlescreen background is cleared (looked weird in Rascall and TIOS)
+ enemies fire at a ### rate instead of firing at will (too random)
# moving enemies dont move off the screen top/bottom (they wait there)
+ seven playable levels going easy to hard (including moving enemies)
# xtraInfo data wasn't reset when a moving enemy entered the game
* longer delay when level's completed (NextLevel screen came too soon)