Remove testbed remnant

"MAYBE" was the test trait for prereqs2.  You needed (("CLAWS" ||
"CLAWS_RETRACT") && "PREREQ") to get "MAYBE".

The Threshold trait was UHUH and the test-trait that required it was
NOPE, incidentally.  Dev trivia FTW.
Merge pull request #5288 from KA101/LabNoteEnabling

Lab-note mining
Merge fix to hammer-based dissasembly.
Merge batch of enhancements.
Survivor mask reshuffle

Per IRC discussion with Rivet, all survivor masks are now made with a
fabrication roll and use Tailoring for a support skill.

Standard masks are still Tailoring, though the XL gas mask now needs a
point of fabrication to expand an existing mask.
Rearrange order of evaluation for tough and flimsy traits so only most extreme ones apply.
Restyle item_groups.json.
- delete 'genderswap' window;
- one more border_color instead of lt_gray
changed multidrop to store taken off items into a separate vector
added calculate_drop_cost to calculate hove many moves it takes to drop some items
use that function in game::drop
add a wrapper to provide the old game::multidrop function that returns all dropped items in one vector
take time to take item off, even when called from game::inventory_item_menu
upped radiation damage
insignificant stuff for flexibility
multidrop tracks the freed volume capacity and calculate_drop_cost uses it
give items used to describe the crafting result a proper birthday
0 -> NULL, remove unused function declaration, make forced_gate_closing private
fix build error
update vehicle cache to see rotate vehicles
remove unused tmpveh variable, remove unnecessarily test
move vehicles to the correct (rotated) submap