This is a general tidyup to detach this fork better from Gordon, who was (and perhaps still is) completely inundated with WiringPi-related support questions.

This changeset includes a number of tweaks which should reduce support burden on Gordon. I believe they are essential if we plan to release a new debian package.

They should - hopefully - not reduce or make ambiguous the origins of this code while achieving the above.

* Remove Gordon's email address from all source files to avoid support queries finding their way to him
* Update wiringPi URLs to the GitHub repository to try and keep bugs/issues within the fork
* Bump version to 2.70 ready for a debian package release
* Update debian package maintainer info, add bugs & homepage URLs to this repository

It's not perfect - there is no symbol versioning, and I have had to
make some (perhaps false) assumptions about library ABI stability, but
it does produce something vaguely resembling what would be expected
from a library package found in Debian, and it does so using the
standard Debian source format.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>