When a bomber crashes, print details (to stderr for now)
Report crash positions relative to a table of locations

Also the positions of sited flak, if that's the killer
Fix sign-error bug in direction calculation for describe_location
Describe location and cause of fighter crashes, similarly to bombers
Remove now-unused RB_atime_image (attack time graph)
Show the kills on the UI
Perform image resizing in load_data, instead of at every user
Various UI tweaks to the kills display
Decrease the probability of (day)fighter fuel exhaustion
More tweaks to the kills UI (changed some colours)
Centred the text vertically in the Kills UI

Also refactored the kills UI code to be mostly shared between bombers
 and fighters.
Add dat/locations to install.py manifest
Fix some bugs in load_data wrt. converting missing bomber pictures
Add some missing images (xbombers, tick/cross) to install.py manifest