Fix server freeze on client absence.
Add Mods.Common reference to Mods.Cnc
Move Smoke effect, ContrailFader effect, SmudgeLayer and LeaveSmudgeWarhead to Mods.Common
Move PlayMusicOnMapLoad to Mods.Common
Move ResourceClaim and ResourceClaimLayer to Mods.Common
Bring Mods.Common includes in alphabetical order
Merge pull request #6546 from huwpascoe/freezefix

Closes #4591
Merge pull request #6663 from reaperrr/common-stuff4

Moved more stuff to Mods.Common
Use the existing SpriteLoader cache for tilesets.
Use SpriteLoader for frame exporting.
Remove --transpose utility command.

The engine has supported transposed sprites for a long time now.
Add plumbing for mod-defined sprite loaders.
Move ShpTD sprite loading into Mods.Common.
Move ShpTS sprite loading into Mods.Common.
Move R8 sprite loading into Mods.D2k.
Move TmpRA sprite loading into Mods.Common.
Move TmpTD sprite loading into Mods.Common.
Move TmpTS sprite loading into Mods.TS.
Move ShpD2 sprite loading into Mods.Common.
Remove the remaining legacy sprite plumbing.