* Modified the upgrade limits, to both be uniform and allow upgrades for
every factor. (In fact, each one can be upgraded exactly once now.)
* Gave triple-spread weapon double damage.
* Micro rocket damage down from 7 to 6. Total damage is now equal to
double rockets.
3 damage? Really?! No wonder this weapon felt so weak compared to
the double rockets!
I've increased the damage to 7, which causes the total damage of the
weapon to be 35 (slightly more than the total damage of the double
rockets, which is 30).
The source code contains routines to initialise all these resources, but also
functions to load from and store to external files. Support for external files
has now been removed; this removes a potential difference between compiling
with or without USEPAK, and makes it easier to change missions in the code.