Support Agilent Masshunter auxillary file formats

[bovee]

There are a couple files that store pressure, temperature, etc info about a run in a CG file that we should support. There's also an XML "acquisition" file that has some of the run metadata, but not really clear how closely this fits entab's intended use case.

Existing implementation here:
https://github.com/bovee/Aston/blob/master/aston/tracefile/agilent_extra_mh.py