[File] PRONOM signature conversions

[Gregory Lepore]

@jason and @christos

Thank you for looking over the signatures I submitted. Unfortunately my 
conversion code from PRONOM to file format had a bug where multiple 
SubSequences in the PRONOM XML file were not properly identified. I have 
updated the code and the output file on GitHub to properly convert these 
signatures.

0   string  \x46\x4f\x52\x4d    Amiga Metafile Format
is now:
# Amiga Metafile Format
0    string    \x46\x4f\x52\x4d    Amiga Metafile Format
 >8    string    \x41\x4d\x46\x46    Amiga Metafile Format

0   string  \x46\x4f\x52\x4d    Extended MIDI Audio File
is now:
# Extended MIDI Audio File
0    string    \x46\x4f\x52\x4d    Extended MIDI Audio File
 >30    string    \x58\x4d\x49\x44\x46\x4f\x52\x4d    Extended MIDI 
Audio File

0   string  \x46\x4f\x52\x4d    FAXX IFF Facsimile Image
is now:
# FAXX IFF Facsimile Image
0    string    \x46\x4f\x52\x4d    FAXX IFF Facsimile Image
 >8    string    \x46\x41\x58\x58    FAXX IFF Facsimile Image

0   string  \x46\x4f\x52\x4d    IFF Amiga Contiguous BitMap
is now:
# IFF Amiga Contiguous BitMap
0    string    \x46\x4f\x52\x4d    IFF Amiga Contiguous BitMap
 >0    string    \x41\x42\x49\x54    IFF Amiga Contiguous BitMap

At the moment I am using byte sequences for everything, although looking 
at other file signatures it appears they could be ASCII as well. Is 
there anywhere that the file signature format is documented? Also, is 
there a standard test corpus of files that I can use to ensure there are 
no collisions between my signatures and existing file signatures?

Please look over the signatures again and let me know what additional 
work I need to do.
https://github.com/gleporeNARA/pronom-research/tree/master
thanks.