log_runtime, ETH_P_ALL and PcapTimeoutElapsed are used in this code but are not imported. This causes sniff and sndrcv functions to fail on windows.

* Support (BPF) filter in sniff() with offline parameter set

Fixes #393
Also, fixes #355

* Add tests for wrpcap() and sniff(offline=)

as suggested by Guillaume.

Also, cleanup regression.uts since it was a pain to find a place
to add those tests.

* Fix PATH for tcpdump with non-root user

* Do not run tcpdump tests when tcpdump is not available

* Appveyor tests: install WinDump.exe

Thanks @gpotter2

* Some new Windows links

Replaced links for PyWin32, Winpcap, pyreadline

* Update compatibility.py

Moved all modifications to modules not needed in arch that were causing
crashed to another file next to __init__ (in arch.windows).

Fixed "run_tests.bat" crash: the old usage of the %DATE% param was no more supported.