deserialize ability supports ghost mode (move through solids) at higher versions
rename move_object to move_character, and let it take x, y instead. Create a helper that also takes direction. Allows for directional movement as well as blinking ability while reusing code.
use update_block_matrix() instead of direct access
add CHANGES file and update todo
replace model's KillCharacterEvent posts with the kill_object (to be renamed kill_character) call, which will post the former event for us, and handle game messages too.
a small chance that a code freeze is deadly
upgrade descriptions
todo better upgrade info screen
line of sight exclusion: the start and end points
fix bogus line of sight test
upgrade description in spec
bug: exploit resolved before it's game message