Split code into modules, handle USR1, minor fixes.

[reservoir_sample] / README.md

# reservoir_sample #
This is a small unixy command-line utility which will harvest an evenly-weighted random sampling from its input stream.

## what ##
While this sort of collation function can easily be implemented in a few lines of shell, here is a standalone utility specifically for the task, with a few frills.

## who ##
Justin Wind <justin.wind@gmail.com>

## license ##
cite or blame, as apropos
corrections appreciated
no warranties implied