master server has been migrated to new machine and DNS

closes #5748
Merge pull request #5780 from Mailaender/master.openra.net

Changed master server URL to openra.net subdomain
Fix TS refinery and repair pad using snow gfx

Until we support TS theater-specific graphics, we should stick to one of the theaters, temperate in this case.
Use Prerequisites: ~disabled for unbuildable actors.
capturable production queues
remove unused copy pasta from TD
document the buildable and country trait
document another trait with some kind of prerequisite
add a missing space for multi line property documentation
remove pill boxes and hijacker from Allies02