Jumpdist.lua

It seems that in almost every case cargo_common.lua has been used it has not worked so contributors have also added jumpdist.lua to their missions to make things work... what really needed to happen was for jumpdist.lua to be added to the cargo_common.lua script. This pull request is on top of my other master pull request (apologies... I'm a bit new to this but I think I have it figured now...) to add in the "include jumpdist.lua" to cargo_common.lua and remove all the unnecessary includes in the mission files. Essentially cruft removal.