Backward compatability for comments in simulation (MPSIM) file

[pfjuckem-usgs]

Item (line) 3 of the MPSIM file contains a series of numerical values that cover a range of settings. Rather than having to refer back to the documentation, it's nice to add a comment to that line (following a #). This was possible with the "official" release of MP7. The provisional version of MP7 threw an error, which was easily overcome by deleting the comment (actually moved it to the header, or "item 0"). This is a rather minor issue, but it's nice to maintain backward compatibility, and this particular line controls several important settings. Moreover, comments on other lines of the MPSIM file did not cause an error.

[aprovost-usgs]

@pfjuckem-usgs Thanks for reporting this issue. An additional setting was added to that line. To allow mp7 simulations without that additional setting to still run, it was made optional (at least provisionally). The catch is if you have a comment at the end of the line, which is not uncommon, it tries to read the additional setting and fails. I'll consider how best to incorporate this parameter "permanently." It might be that old files without it will need to be updated, but in any case it does need to be handled more gracefully.