Verona spec:: $BUILD

[Iris Clark]

Hi.

For $BUILD, we needed to add '0' as a legitimate value to act as a sentinel.  

Because we consider builds to be version numbers for releases under development, we must alter the spec to consider $BUILD when comparing version strings, even though it violates the semver.org definition.  Thus, we needed to clearly specify how comparison will be handled for 0, non-zero, null values.

The following spec changes should address both of these issues:

156c156
<   - <a name="descBUILD"/> `$BUILD`, matching `([1-9][0-9]*)` --- The
---
>   - <a name="descBUILD"/> `$BUILD`, matching `(0|[1-9][0-9]*)` --- The
160,161c160,163
<     When comparing two version strings the value of `$BUILD`, if present,
<     is always ignored.
---
>     When comparing two version strings with equal `$VNUM` and `$PRE`
>     components, a string without a `$BUILD` component is always less than
>     one with a `$BUILD` component; otherwise, `$BUILD` numbers are
>     compared numerically.

Please let me know if there are any concerns.

Thanks,
iris