Dcm2atr

** dcmtoatr.c -- written by Chad Wagner
**
** I just wanted to throw in some personal comments, I wanted to thank
** Preston Crow, for his work on portability issues, as well as some of
** the ideas he put into this program, Bob Puff, for his hard work on
** The Disk Communicator, an excellent means for transferring disk images,
** and I feel it is the de facto standard, and should remain as such, and
** Jason Duerstock, for writing DCMTODSK and his documents on the DCM
** format, which did help me resolve some of the things I wasn't aware of.
** I am sure there is a few others.  Unfortunately I only got one response
** from Bob Puff, he was attempting to help, but I believe he is very busy
** person, and just didn't have the time.
**
** Revision History:
** 31 May 95  cmwagner()gate.net
**  1 Jun 95  cmwagner()gate.net
**       added in some portability macros from dcm.c
**       added in read_atari16() function from dcm.c
**       wrote write_atari16() function
**       did a general clean-up of the code
**  1 Jun 95  crow()cs.dartmouth.edu
**       did a clean-up of the code, hopefully resolving any
**         portability issues
**  2 Jun 95  cmwagner()gate.net and crow()cs.dartmouth.edu
**       Allow for multi-file DCM files, after they've been
**         combined into a single file
**  5 Jun 95  cmwagner()gate.net
**       Fixed decoding routines to handle double density diskettes
** 26 Jun 95  cmwagner()gate.net
**       Added in support for creating DCMTOXFD, default compile is
**         for DCMTOATR
**  3 Sep 95  cmwagner()gate.net
**       Added in -x switch, which creates an XFD image, instead of the
**         default ATR image.
**       added in soffset() routine, changed around the SOFFSET define,
**         so that xfd images could be created, without compiling a
**         different version.
**       26 Jun 95 modification is no longer relevant because of this
**         modification.
**       wrote some more comments, about what certain functions are doing,
**         when they were created, and who wrote them.
** 28 Sep 95  lovegrov()student.umass.edu
**       Fixed bug in soffset() function, apparently sector 4 would return
**         an offset of 16 for ATR images or 0 for XFD images, which is not
**         correct.