Restart select when we see a EINTR

This fixes erratic behavior when scapy is run inside of a separate
thread or in another process.
The patch is taken from
https://bitbucket.org/secdev/scapy/issues/473/scapy-sendrecv-selects-eintr-problem-in

Code cleanup / optimization

Bluetooth: Add HCI LE Create Connection Cancel & HCI Disconnect packets

Introducing the SCAPY_USE_PCAPDNET environment variable

Bluetooth: add EIR / BLE Advertising packet classes

* PacketList.conversations(): include ARP packets by default

* PacketList.conversations(): accept a label instead of counting

* PacketList.conversations(): display the label in the graph

Python 2.5: fallback implementation for gcd() without pycrypto

This was reported by @AmedeoSapio in #68

Fix Issue #115

scapy/arch refactoring

Replacing | with or

Useless line break

Fix TCP & UDP checksums when IP layer has options

Don't use /bin/bash in run_tests

Issue #110 fixes

Accept SCAPY_HISTFILE env var to set scapy hitory file (fixes #103)

python --version may output to stderr (fixes #101)

Reported by Runa Barik on Scapy ML.

Sniff can accept a list of interfaces (+ fixed bug)

Move get_if() to scapy/arch/common.py

Pad packet when needed