MadGraphControl SUSY: Allowing multiple input LHE files

Some of the manipulations in the SUSY post-exec assume that we have a tarball as input, which happens when a single input file is used. When multiple input files come in, we have an LHE file as input, and in that case we need to handle things a bit differently (mostly avoid all of the tarball manipulations and instead treat the thing as a text file directly).

Please give these changes a try, @mamuzic , @dhirsch (or whoever's job this was that was having trouble).