Tidy up version numbering.

[jonm]

We (ok, I) have been doing git tags for releases like "v0.1.9"
but this results in the use of that version string downstream.
For example, make dist will produce sillymud-v0.1.9.tar.gz
instead of the desired sillymud-0.1.9.tar.gz. This change
just strips the leading v off the tag name to use for the
autotools version.

However, I would also be ok with going back through to update
the git tags to be the version numbers we want (0.1.9) under
the assumption that probably no one would care. Putting this
PR to collect opinions on the best path forward.

[dangitall]

I have no strong preference in either direction. I've always use a leading 'v' so it just looks right to me, but that's no reason to go on with that.

One reason a leading v is helpful, though, is that the git describe should probably look more like git describe --match 'v*' to make sure (well, just be more confident really, it isn't foolproof certainly) we only grab version tags. That is harder if you just use the bare version, I'm not sure the glob syntax is expressive enough.