add output frequency and daily/monthly restarts

[barlage]

Add some output options:

for restarts:

• restart_frequency_s > 0 will produce a restart every restart_frequency_s seconds
• restart_frequency_s = -1 will produce a daily 00UTC restart
• restart_frequency_s = -2 will produce a monthly restart on the 1st of month at 00UTC
• restart_frequency_s = 0 will produce no restart

for output, same as above but with output_frequency_s

Addresses #20