mmirs_qrp: Work with raw data

[astrochun]

mmirs_qrp.main() function with "d-corr" images, which are essentially last - first images determined from the up-the-ramp sampling data. If those "d-corr" files are not available, we need to use the raw data.

[astrochun]

Fixes have been implemented:
0a41822, 7596a13, ee7ac25

Note that an amplifier gain issue is still present to product the true d-corr files.