major update of documentation.  The doc directory now includes

  doc/ccast_intro.pdf  - an overview of design and project status
  doc/ccast_eqns.pdf   - intro to the ILS and calibration equations
  doc/matlab_sdr.txt   - the matlab SDR format field definitions
  doc/finterp.pdf      - some notes on Fourier interpolation
  doc/status.txt       - ccast status report as of 12 Dec 2013

In addition, the main README, source/README, and motmsc/README files
have all been updated.