Also adding in the stuff for /dev/gpiomem with warnings
and information in the gpio manual page (who reads that
though!)

Updated the gpio program to be device tree aware.

help.

We are going to want to introduce a real Debian source package build
system.  But that needs to contain a lot of things in debian/ which
ought not to appear in the .deb made by the existing ad-hoc `./build
debian' arrangements, which we want to keep so as not to unduly
disturb existing users.

So rename the whole debian/ directory to debian-template/ and change
all references in the build system.

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