Jobcode refactoring

This PR in words:
* Much item adding has been generalised and added to the parent job equip proc, equip now calls equip_items along with equip_backpack which is the only procs that should be overriden. equip itself gives the player the basic things, ID, PDA and headset.
* Bunch of variables have been added to the job datum that lets you change the items handed out in the equip proc, much more cleaner than before
* Best of all, before, everybody received the standard PDA, which was then overridden when equip() was called, so the PDA was quickly removed ontop of the job related one, same with ID, same with headset, (I think) same with backpack. Causing unnecessary lag. This has been removed
* It's generally much more clean and maintainable now, easier for noncodeys to edit
* **Every job now receives what they should, no matter if they have backpack, or no backpack, before if you didn't carry a backpack you could miss out on some good stuff, such as stunbaton for sec**

In addition to the job refactoring, I have standardised the PDA and ID naming into one proc, instead of it being spread out at over roughly 13 files.

I have tested this as much as I see necessary, but it's a lot of changes and I can't predict or test every inch of it.

**I would love if you guys gave more ideas for refactoring, especially job_controller.dm file since its messy**