Full Separation of Cargo Department from Civilian

-Moved Quartermaster, Cargo Technician, and Shaft Miner to be part of a
new positions list, removed them from the civilian_positions list
-Reordered and recoloured cargo jobs within the Set Preferences screen.
They now appear in brown and after all civilian positions. This required
creating a separate .dm called dept_cargo.dm, as jobs are read from each
file in code/games/jobs/job alphabetically and placed in the screen in
the order they are read, necessitating the cargo job dm being
alphabetically later than both civilian.dm and civilian_chaplain.dm
-Created new Cargo jobban set, that bans from quartermaster, cargo
technician, and shaft miner
-Modified crew manifest such that all cargo jobs now appear under a new
Cargo subheading.
-Added Quartermaster to heads list in PDA, which was forgotten before
-Added Quartermaster to head jobban list, which was forgotten before
Merge pull request #37 from kbernges/master

Full Separation of Cargo Department from Civilian