Mentor changes.

Mentors no longer see stealthmins
Mentors no longer see antagonists / have check_antagonist verbs
New debug verb:  Reload Mentors (or mods)
refactors some disposals filtering code and remaps some disposals pipes

New things!
/obj/structure/disposalpipe/tagger - retags a holder when it passes through
/obj/structure/disposalpipe/tagger/partial - retags a holder when it passes through two times; good for loop detection
/obj/structure/disposalpipe/sortjunction/wildcard - filters out all holders that are tagged
/obj/structure/disposalpipe/sortjunction/untagged - filters out untagged holders

Tagging doesn't use an icky list index system any more, tags are put into a global list and directly checked against.

Changed the map around a bit, disposals is now a proper loop but anything that's not tagged, is tagged with "Disposals" or anything that passes the tagger twice will be filtered out.

Not a feature, just a fix for drones being sad about weird disposals. <3
Merge pull request #5122 from Zuhayr/master

Fixes a minor icon-flicker thing with the drone fabricator.
Merge pull request #5117 from Ccomp5950/mentor_change

Mentor changes.
Mentor Unnerf.

JMP was doing a rights check in the Topic instead of doing it on the proc, just went ahead and fixed the rights check to include mentors.
Mentors now have player panel but can't see traitor panel.  The idea is so they can't tell who is an antag through this.
Merge pull request #5119 from boopcat/happydrones

refactors some disposals filtering code and remaps some disposals pipes
Merge pull request #5127 from Ccomp5950/mentor_change

Mentor Unnerf.
Serithi's request, taj and unathi spawn with sandals.