added config flags for objectives being enabled or disabled.
added antag options menu.
added ability to choose where a syndicate uplink is installed.
Merge branch 'master' of https://github.com/Baystation12/Baystation12 into antag
Little things

Gave engine room airlock camera x-ray upgrade (so AI can see SMES).

Locked engine room core access doors.
Merge pull request #4350 from Loganbacca/dev-freeze

Minor mapping tweaks
Merge pull request #4351 from Zuhayr/dev

Dev/master merge.
Small borer fix

Someone forgot an exclamation point and made the check for a lack of
brain check FOR a brain, making the assume direct control thing not
work.
Merge pull request #4353 from Furlucis/master

Small borer fix
Stuff.
ugh
Fix handcuff resist - layer bug

Fixes #4324

Resisting out of handcuffs was leaving the handcuffs layer set to 20 (over top of the UI).
Changed it to use the drop_from_inventory() proc so it handles the drop event correctly.
Fix item drop layer bug

Similar to the handcuff resisting layer bug.

When removing an item from your inventory that has associated inventory slots, items that were dropped from the extra inventory slots would be dropped with incorrect layer variables (set to 20 so they were rendered over the UI).
Now when the extra items are dropped, it calls the drop_from_inventory() proc, which correctly changes their layer back.
Fixes #4355
Fixes #4346
Fixes #4306
Generalized yank_out_object().
Fixes #4223
Fixes #4219
Discovered/fixed a division by zero error for standing on the supermatter core.
Fixes #4089
Fixes #4195