Forcefully deprecate meteor_hit()

Created by: dylanstrategie

meteor_hit() is a textbook example of snowflake. What you have here is a proc linked to a single entity (the small meteor) which shouldn't even have it (ever since I reworked meteors, small meteors explode) that is present in FIFTY. FUCKING. FILES.

Since an explosion more than clearly does the damage we want done on meteor impact, it is more than logical to remove it and lighten our code of obsolete and obscurantist procs

For the handful of times where it isn't possible to straight up remove it (immovable rod, dust, small meteor, meteor launcher), the code was quickly patched by making it fire ex_act(2), given that small meteors perform explosion(src.loc, -1, 1, 3, 4, 0)

Doing it quick and dirty because otherwise it's going to cause conflicts everywhere at some point where we have major and important PRs open