Implement support for versioning and release engineering procedures - version 1.2.5.a1
    Instead of changing configure.ac AC_INIT for each version change, there
    is a new file - VERSION.sh.  This file also contains support for creating
    version numbers for pre-releases, and pre-release strings containing git
    commit hashes.
    One of the complications is that AC_INIT does not allow you to override the version and package tarname fields.  We can override them after the fact everywhere
    except in config.h.  AC_INIT defines the following which we would like to override but cannot: PACKAGE_VERSION PACKAGE_TARNAME PACKAGE_STRING PACKAGE_BUGREPORT
    Instead, we define DS_ versions of these e.g. DS_PACKAGE_VERSION etc. and make
    these available with AC_DEFINE(DS_PACKAGE_VERSION,...) etc.
    As an extra added precaution, we undefine these in Makefile.am like this:
    DS_DEFINES = ... \
    	-UPACKAGE_VERSION -UPACKAGE_TARNAME -UPACKAGE_STRING -UPACKAGE_BUGREPORT
    If someone tries to use PACKAGE_VERSION in C code, they will not be able to,
    and will have to use DS_PACKAGE_VERSION instead.  All of the DS code that used
    PACKAGE_VERSION has been changed to use DS_PACKAGE_VERSION instead.
    There is a new make target - git-archive - as a convenience for creating source
    tarballs from git.  By default, the source archive will be placed in the build
    directory - you can specify SRCDISTDIR=/path/to/SOURCES to use an alternate
    dir (e.g. make SRCDISTDIR=/path/to/rpmbuild/SOURCES git-archive to make a
    source tarball for rpmbuild)
    configure will print the branded package name and version
    Reviewed by: nkinder (Thanks!)