(code bounty) refactors all uses of Crossed() and Uncrossed() into signals sent to loc, tracked by connect_loc

[Kylerace]

About The Pull Request

this pr is for a code bounty by @optimumtact

original pr here #58210, can be kept as a backup in case all the extra elements cause ooms or something (probably ridiculously unlikely now that i think of it)

the for loops in doMove and Move that called Crossed() and Uncrossed() on every movable in loc and oldloc no longer exist, now it simply sends a signal to the relevant turf, and if anything on that turf wants to listen to COMSIG_MOVABLE_CROSSED or the uncrossed equivalent, it uses the connect_loc element to listen to the turf. this way you're not calling Crossed() and Uncrossed ~n times each every movement over a tile with n objects in contents.

also changes connect_loc to now register to a new signal, COMSIG_MOVABLE_LOCATION_CHANGE. its emitted right after the moving atoms loc changes in Move() and doMove(). because the crossed and uncrossed signals are emitted before Moved() is called, there are times where a proc registered to crossed can qdel or move the crossing atom, meaning that connect_loc can try to access the targets list with the targets current position which was never put into the targets list because Moved wasnt called yet in the process.

NOTE: for future people using git blame to find this pr, it uses the Moved() signal again not LOCATION_CHANGE

squashable is a component now, with how crossed is changed theres no way for an element to get a reference to its target in any signal handler registered for crossed, since the crossed and uncrossed signals are sent to the turf that its target is on

Why It's Good For The Game

Massive performance improvement when theres many moving objects in a few tiles,

this is how fast the tram moves on master with three part replacers worth of objects on it
https://user-images.githubusercontent.com/15794172/114290043-77dd5100-9a31-11eb-869d-3927582ba064.mp4

this is how fast the tram moves with these changes, same number of objects on it in the same spots
https://user-images.githubusercontent.com/15794172/114290056-95121f80-9a31-11eb-910f-d28a24cb17a8.mp4

Changelog

🆑
refactor: tram is marginally faster
/:cl:

[Mothblocks]

TM'd on Terry, will merge if no complications (or if they're extremely minor).

[optimumtact]

bot says no lol

[Mothblocks]

et tu, brute?

[rdragan]

This seems to have broken at least teleporters, wormholes(from the wormhole event), wormhole jaunters and hand tele portals.

[ATH1909]

This seems to have broken at least teleporters, wormholes(from the wormhole event), wormhole jaunters and hand tele portals.

we should probably check to see if it breaks monkey diving and mulebots as well.

[KathyRyals]

Can confirm this broke portals.