Full support for strict / warn features.
Full support for strict / warn features.

By default user is not allowed to build broken packets
(like IP as a payload of TCP). UMPAStrictException is raised then.
But we can simple pass strict=False to the constructor of Packet
(or later).
Also we can switch on/off warnings messages if strict=False.
Default is on.


git-svn-id: ee7a57951e762bd0bd73821a456cc95fa2e543d2@3352 1105ee14-b0fa-0310-85a5-ff3eed429ff7

umitproject/umpa,umitproject/umpa