Fix file path names, path_info has no 's' there.

That's why you use global constants which contain the literal string once, and you refer to those constants instead of writing the "same" literal string again and again.
Merge pull request #9882 from BevapDin/fix-save-default-mods

Fix saving default mods list
Export compare_by_dist_to_u to Creature class

And make it more generic by adding the position of g->u as member.
Export code to gather visible monster in range into function.
Make re-targeting on burst fire simpler:

Use player::get_visible_creatures instead of manual iteration, includes npcs.
The function also checks the range and the visibility, so that's not needed later.
Store a temporary value in a variable.
Check for any kind of target before re-targeting.

This includes npcs and even the player itself (think npcs firing).
Remove pointless assignment.