[MEDIUM] stats: add the ability to dump table entries matching criteria

[MEDIUM] stats: add the ability to dump table entries matching criteria

It is now possible to dump some select table entries based on criteria
which apply to the stored data. This is enabled by appending the following
options to the end of the "show table" statement :

  data.<data_type> {eq|ne|lt|gt|le|ge} <value>

For intance :

  show table http_proxy data.conn_rate gt 5
  show table http_proxy data.gpc0 ne 0

The compare applies to the integer value as it would be displayed, and
operates on signed long long integers.