timing_model: rename some functions
timing_model: start at defining how to compute delay/phase.
Merge branch 'jing'
Inserted some of Paul's TOA reading code.  Does not work yet.
Added tilde files
Added some basic information to the README including team and philosophy
Added a data directory
Added some ephemeris stuff
Added simple download script for ephemerides and Earth-rotation info
Added a couple more SPICE requirements
Added a couple of other required constants files
Improved the example for loading the kernels (including environment variable)
Fixed typo
Can read TOAs.  Added observatory data file parsing.
tempo2 earth position test. still not quite the same