[MAPINFO] Specifying Episodes in UMAPINFO and RMAPINFO Creates Duplicate Episodes

[andrikpowell]

There's a bit of weird thing when Doom Retro reads both UMAPINFO and RMAPINFO, in that if they both specify episodes, it'll show up as duplicated episodes in the episode screen.

Personally, I solved this by removing the episode declaration in the RMAPINFO lump, but it may be a good idea to create some kind of exception to fix this.