configure: fix version and copyright

Version will be the standard for a preview version (x.99.y), where `y`
be the subsequent previews (being a preview means it will be somewhat
allowed to break API). `x+1.0` is normally the target for the FINAL
release.
configure: define version only in one place

S.P.T.: Single Point of Truth
.gitignore additions for a sane git-gui summary
Merge pull request #6 from knocte/master

Several versioning and gitignore polish