take no chances with the data patch

people don't seem to want to download the data patch themselves, so i guess
we need to take a more aggressive attitude toward these annoying little map
bugs. this one fixes the skyranger cockpit and the walls on the lightning.
shave off some semicolons

aesthetics.
method for marking tiles as "dangerous" to the AI
danger zone checking for alien AI behaviour

as well as a small refactor to check target validity, incorporating
danger zone checks.