fix nsh len field init

Since MDType default value is 1, set Len defautl value to 6

Also add a post_build function which sets the len value to len(pkt)/4

fix scapy tests accordingly

Support (in contrib) for MQTT (Message Queue Telemetry Transport) protocol, with tests.

[coverage] More tests for inet.py

Modify information about sr() and fuzz()

Cleanup Nmap module, add tests

Added information about sr() and fuzz() functions, nothing important but useful as well.

Signed-off-by: Fernando Fernández <ffernandezmancera@gmail.com>

[TLS] Unify UTCTimeField (small)

Replace the UTCTimeField occurences (one in ppi_geotag.py, one in dhcp6
and one in tls/handshake) by a single one

[Python 2 to 3] Remove longs and fix octals

[coverage] New tests to avoid randomness of coverage

[SCTP] RFC 4895 & 5061

Fields/BitField: implement .i2len()

[coverage] Small tests

to reduce the randomness of coverage

EAP - fix variable length field computation

[Routing/Windows] Improve routing system

add bindings for NSH over GRE

Updated/fixed install doc

Added some pipe objects

Signed-off-by: Gabriel Ganne <gabriel.ganne@enea.com>

[rewritten] PR #280

[coverage] Answering machines unit tests