Use built-in autotools for packaging and tests

In preparation for the 0.8.2 release, fix up the distribution code:

• Replace some of the roll-your-own scripts with the tooling that autotools actually already has in place.
• Actually run the new tests as part of the test build and use make distcheck to verify the generated tarball.
• The distcheck uncovered an issue with missing files and improper test file paths which are fixed in the MR as well.
• Integrate a version generation script (happily pulled from the autotools project itself) with the autotools configuration so that all the version information is properly annotated in all the right places.

@timsoft As an FYI if you want to glance at this (but I'll plan to merge now). I'll be posting a release candidate soon.