4dfp support

[effigies]

The 4dfp out of Washington University is still being used. I ran across a need to use it while reproducing some Midnight Scan Club analyses, and a Python interface would have been nice to have.

Some references (lots of duplication of the same one or two docs, but in case there are meaningful differences):

• https://4dfp.readthedocs.io/en/latest/format.html
• https://dosenbachlab.wustl.edu/wiki/4dfp/
• ftp://imaging.wustl.edu/pub/raichlab/4dfp_tools/
• https://github.com/DosenbachGreene/4dfp_tools
• https://mvpa.blogspot.com/2015/04/format-conversion-4dfp-to-nifti-plus.html

[effigies]

• .4dfp.hdr is a modified ANALYZE 7.5 header, defined in NILSRC/TRX/ANALYZE.h
• .4dfp.ifh is an Interfile (spec (docx)) header, defined in NILSRC/TRX/ifh.h

[effigies]

Existing Python implementations of IFH parsing:

• https://github.com/karchie/py4dfp/blob/master/py4dfp/ifh.py
• https://github.com/spedemon/interfile