Avoid duplicating output to stdout if using -t without a file name.
Add -u to llogger to print in UTC (which was the default before); fix
documentation to show the output file name as optional.
Add -s (sigfigs) parameter to llogger.
Change llogger to truncate logs instead of append unless -a given.
Add -t flag to llogger to tee the output.
Make llogger line buffered.
Explicitly mark llogger timestamp as being UTC.
Add util directory for utilities only marginally related to the GDP.
The first entry is llogger, which is kind of like logger(1) but it logs
to local files instead of syslog. It is intended to timestamp debugging
output from gdplogd and gdp_router_click.