This commit adds a Lua interface that allows Lua scripts to directly
query flows with a simple SQL-like statement. This also enforces the
checks and data conversions in the iface_ports_list.lua script.
This commit adds a first option to filter results of queries
on flows so that only relevant info can be returned. This for
now only introduces a PORTS filter. This helps reducing the
load on the Lua stack when the flows limit is high.
This commit lets the iface_ports_list.lua invoke getFlowsInfo()
with the host filter when the host parameter is not nil, so that
the Lua stack is not overloaded when possible.
