Adopt true semantic versioning

[terrillmoore]

The version numbers in our BSPs are semi-semver 2.0 compliant -- but the fourth field local is compared numerically rather than semantically. It's supposed to be a pre-release, and 0 is supposed to be less than any other.

The simple way to fix this is to retain the numerical values, but introduce comparison macros that knows the rules.

Luckily existing uses will not be affected (if you think through the existing uses, which numerically are comparing to older versions that differ by more than the local/prerelease field. So this doesn't drive a major version increment.