Changed max length to 1024.
Made it -fPic so it will work with a python library (should be harmless for other use)
Added nipp_copy_message()
Fixed boundary bug in nipp_truncate()
Fixed bug in nipp_send() so it zeroes the checksum before creating a new one.
Added more field extraction macros.
Added a bevy of field modification macros.
Added prototype for nipp_copy_message()