The crate published to crates.io will always include the major and minor simavr version in the crates.io version.
The revision is specific to this crate.
Versions look like this
<simavr-major>.<simavr-minor>.<simavr-sys-revision>
So, if we've made two revisions with simavr 1.5.9, then the new version
should be 1.5.1.
When a new minor version is released, the minor version should tick back to zero.