Clean up refinery and harvester docking sequence logic

This has been bugging me for a long time now, so I finally decided to address it.
@Phrohdoh mentioned a few days ago on IRC that he wants to do some work on refineries, so if this is conflicting with his work we'll just close it for later (if needed), since it's not a feature or a bug fix.
Basically what I did:
 - Rename TiberiumRefinery -> TiberiumDawnRefinery (only Tiberian Dawn mod uses it)
 - Rename HarvesterDockSequence -> TDHarvesterDockSequence (same reason)
 - Rename OreRefinery -> Refinery  (since both RA and Dune 2000 mods uses it)
 - Rename RAHarvesterDockSequence -> HarvesterDockSequence  (same reason)
 - Fixed a typo in RefineryInfo's DockAngle's description
This wants to make use of an enum instead as only two values are allowed. Otherwise it will also be hard to guess what to type in here when just looking at the https://github.com/OpenRA/OpenRA/wiki/Traits documentation.