Allow IDCLEV0x to warp to current episode in Doom 1

Mostly a test to see if I have the hang of git basics, but also a nice
feature I think.
Preserve tab indents; allow IDCLEV00 to restart current map.
Merge pull request #44 from plumsinus/master

Allow IDCLEV0x to warp to current episode in Doom 1 and IDCLEV00 to restart current map