* make top N AS intervals configurable (see config.inc), and allow
separate top stats file to be used per interval (enables e.g. proper
weekly/monthly stats)
* add Terabyte formatting
* add warning when trying to use peer-as stats with NetFlow
* slightly optimize packet handling when peer-as is disabled
* default peer-as stats to disable
sFlow and Netflow v9/v10 may provide VLAN information in flows, so
one can distinguish between different logical links on the same
physical connection (e.g. transit via private VLAN over IXP).