ai spacecarp hologram
Changes the layer for items on trays to -1.  This makes them display on top of the tray, but not above other things.
Oh, not in cruelty, not in wrath
  The Reaper came that day;
An angel visited this damned sat,
  And took the parapen away.

Replaces parapen with sleepypen that contains 30u of sleeptoxin and 30u of a new mutetoxin that makes you unable to speak.

Mutetoxin can be made with 2 parts uranium + 1 part water + 1 part carbon.
Refined the implementation of the AStar algorithm :

*Reorganised and commented used procs for better visibility/maintenance
*Redid the PriorityQueue class
*Changed the euclidian distance to the byond one (so that we don't calculate float and square root when it's not necessary)
*Made the AStar algorithm use the closed list instead of just filling it
*Some optimization in the open list sorting : last entered is first in case of f ties, slightly less tiles are checked now
*Changes the order directions are checked when adding adjacents turfs to make for more 'realistic' path (read less 'drunk pathing' with lots of diagonals)
*Fixed some turfs densities not being check for diagonal movement
*Closed firedoors are now correctly seens as blocked by the algorithm
*Cleanbots now only moves in cardinal directions, like other bots.
*Updated the info text at the beginning of the file a bit
*Absolutely unrelated : simplified the turf.Bless() proc
PDA - Security Records were missing tables.
Fixed a bug where printing would stop working if a record was deleted.
Merge pull request #4125 from Jordie0608/mygrandmacheatedconstantlyatsnapwheniwasatoddler

AI spacecarp hologram
Merge pull request #4135 from Rolan7/Issue_1919

Fixes tray layer issue
Merge pull request #4138 from Menshin/LetsBeAStar

Dedust an ancient dark ritual : A*
Makes C4 unable to be planted on mobs and reduces C4 cost to 1 TC
Merge pull request #4059 from Miauw62/goodbyeparapen

Replaces the parapen
Changelog for #4059
descriptive commit name
Merge pull request #4157 from Miauw62/changelog894684

Changelog for #4059
Merge pull request #4144 from Rockdtben/securityPDA

PDA - Security Records were missing tables.
Merge branch 'master' of https://github.com/tgstation/-tg-station.git