deb/rules: drop the self-remaking parts

The code in debian/rules for rebuilding debian/control has been broken
since the start, and the code for re-running debian/configure is about
to be broken with the new changes demanded by the unified-build-candidate
branch.
deb/rules: remove unused python_version
deb/rules: dont need to care about BUILD_SYS

The -X argument to dh_fixperms says to eXclude linuxcnc_module_helper
when it's fixing the permissions on all our files.  But dh_fixperm won't
complain or fail if it doesn't find linuxcnc_module_helper, so we don't
need to do this substitution trick to tell it what to expect.
deb: dont ignore package-dirs we no longer build
deb: new debian/configure and debian/control*

This one's written in python instead of bash, and has a cleaner internal
structure.

This handles the flavored debs of the unified-build-candidate branch.
deb: get rid of ancient Provides in control

I think it's time to stop worrying about users upgrading from emc2.deb
packages.
deb/conf: accept -a to mean -r

"debian/configure -r" is supposed to mean "configure for the running
realtime kernel", and "debian/configure -a" is supposed to mean "configure
for any realtime headers you can find on the system".

The buildbot ill-advisedly runs 'debian/configure -a', even though it
knows it's going to run runtests later (so the kernel it builds for must
be the one that's running).  So really -r would be more correct.

In practice it's fine because all the buildslave VMs only have one
realtime kernel installed, so there's no difference between -a and -r
on those hosts.

If someone cares strongly about the difference between the old "-a"
and the new "-a" we can reinstate it.

As an aside, it probably makes sense to add a "debian/configure --all"
option that examines the apt database and makes the dsc build-depend on
all *available* realtime kernel headers.
deb/control: relax the Conflicts

The flavor packages should conflict with pre-ubc packages, but there's
no convenient way to specify that currently.

When we merge ubc into master we'll tag that point as 2.6.0-pre1,
and make the post-ubc debs conflict with linuxcnc < 2.6.0-pre1.
deb/rules: dont use cpio when cp will do

Debian Wheezy doesn't come with cpio by default, this commit lets us
not add a build-dependency on it.
fix linuxcnc launcher script for new ubc substvars
fix inivar path in linuxcnc launcher and realtime scripts
deb/conf: start handling xenomai and xenomai-kernel flavors