app-layer: proto detection update

Instead of the notion of toserver and toclient protocol detection, use
destination port and source port.

Independent of the data direction, the flow's port settings will be used
to find the correct probing parser, where we first try the dest port,
and if that fails the source port.

Update the configuration file format, where toserver is replaced by 'dp'
and toclient by 'sp'. Toserver is intrepreted as 'dp' and toclient as
'sp' for backwards compatibility.

Example for dns:

    dns:
      # memcaps. Globally and per flow/state.
      #global-memcap: 16mb
      #state-memcap: 512kb

      # How many unreplied DNS requests are considered a flood.
      # If the limit is reached, app-layer-event:dns.flooded; will match.
      #request-flood: 500

      tcp:
        enabled: yes
        detection-ports:
          dp: 53
      udp:
        enabled: yes
        detection-ports:
          dp: 53

Like before, progress of protocol detection is tracked per flow direction.

Bug #1142.
proto-detect: update port logic

If a flow matches both an 'sp' based PP registration and a 'dp' based,
until now we would only check the 'dp' one. This patch changes that. It
will inspect both.
proto-detect: masks cleanup

The direction specific masks were not used correctly. The toserver ones
were only used for 'dp' registrations, the toclient ones only for 'sp'.

The patch merges them.