Merge pull request #13 from dwtj/master

Debugging with calibration
Made song test code in `main()` into its own mode to be selected.
Encoded OI stop values
OIStopID
Can now use `sensors.calibrate_dist()` to generate calibration data!
Fixed bugs in `gen_servo_converter()` and `gen_ir_converter()`.
Created stub for `calibrate_cliff()`.
Merge branch 'master' of https://github.com/aore/mars-rover
Implemented `oi.dump()`.
Working to get `ir.dump()` to work.
`oi.dump()` and `calibrate_cliff()` now work.
Renamed `open_interface.c` to `oi.c` to match subsystem naming
conventions.
Renamed `open_interface.c` to `oi.c` to match subsystem naming
conventions.
Merge branch 'master' of https://github.com/dwtj/mars-rover
Made a stub for `objects.py` and created `gen_dist_converter()`.
Fixed `sensors._gen_dist_converter()`. Added `plot_conv` functionality
to the distance sensors' converter generators. Also moved the scripts
used to generate calibration data into their own folder, `calibrate`.
Added some initial calibration data that will need to be updated.
Added initial work on the `Rover` class.

It encapsulates a sentinel object and calibrated conversion objects.
It will handle the scanning behavior.
Reverted the `open_interface` name changes.
Removed calibration data from the repo, and added the directory
which will hold this data on local repos to the `.gitignore` file.
song fixes