Create an MVP frequency correction script in C

[pyuxiang]

Relevant equation found in #6.

Perhaps we can name it freqcd for the frequency correction daemon, styled after the error correction package named thusly errcd.

Relevant parameters are:

• Pipe for (64-bit) timestamp events
• Frequency correction offset (either in floating point, or integer with specified units)
• Output pipe for corrected events (to chopper)

Might need to manually track overflow in timestamp events, as well as truncate back to 64-bit. Reference start time will correspond to the first timestamp event entering the pipe.

[pyuxiang]

Closed with commit 82b84bd.