The Temperature Gun Update

I like calling my pull requests "updates" don't I?
Anyway, here's a fancy png to announce the grand revival of the temperature gun.

![temperature](https://cloud.githubusercontent.com/assets/7573912/4605468/84cf561c-51e3-11e4-9912-fea92231110e.png)

and here's a clearer changelog:
-Temperature guns now apply their selected temperature to their projectiles
-It finally has its own item_state icon, with variations depending on the current temperature
-The projectiles have various colours as well depending on their current temperature. They are now also 8-directional. The old temperature gun used ice_2 which only had 4 directions.
-Temperature guns now slowly recharges 50 charge every 2 seconds. It takes 12 seconds to recharge a max level beam. the gun has enough capacity to fire 3 max level beams at once before being completely depleted.
-Temperature gun size increased. They can't be put inside a bag anymore, nor placed on the belt slot. They can however be fit to the back slot, like shotguns. (because it needed at least one nerf)
-Temperature guns spawned at R&D do not appear inside of a lockbox anymore.
-Temperature gun can be emagged, increasing the maximum target temperature from 500 to 1000
-Any Beam dealing over 501 damage will set their target on fire. Those searing beams have a distinctive appearance.
-The temperature gun also has a distinctive sprite when its current temperature is above 501K

Changes done to features related to the temperature gun:
-projectiles now have a new proc that fires right when they get fired. was necessary to allow temperature beams to match their gun's temperature.
-slimes now take 301 tox damage per tick instead of 200 when their body temperature is below 50K (this check was probably meant to instantly kill slimes, but the coder forgot that even though adult slimes only have 200hp, the don't die until they reach -100hp)
-Syndicate Energy Crossbows spawned from R&D now appear inside a lockbox (this one was just next to the temperature gun's design. I found it pretty ironic that a syndicate energy crossbow doesn't require a secure lockbox while a temperature gun does, so I cut-pasted the lockbox requirement from one design to another)