Desc*.pm:
- open Desc in safe mode (drop priv to $USER)

ICMPv4:
- TYPE_PARAMETER_PROBLEM, TYPE_SOURCE_QUENCH

NEW.pm:
- StreamTCP
- StreamUDP
- ICMPv6
- IP reassembly
- TCP reassembly

Dump.pm:
- also put a pointer to outgoing frames in sortedFrames->{out}
  => put a ->out accessor in Frame object
  => put outgoing packets refs into a hash ? (to avoid user storing it, and
     avoid duplicated packets into memory)
- sort ICMPv4 differently for UDP request than TCP request

Env.pm:
- make a good error handling scheme ($Env->err && $Env->errString)
  => ETIMEOUT, E...
