Include dashes in build meadata, e.g. 0.1.0+SNAPSHOT-123.git456

[binwiederhier]

Hi, thanks for the library. In bullet point 10, semver 2.0.0 states about build metadata: "Identifiers MUST comprise only ASCII alphanumerics and hyphen [0-9A-Za-z-]."

You library currently complains that "0.1.0+SNAPSHOT-123.git456" is not a valid version. I tried fixing the regex in Regex.php to private static $version = '/^(?<version>[0-9]+\.[0-9]+\.[0-9]+)(?<prerelease>-[0-9a-zA-Z.]+)?(?<build>\+[-0-9a-zA-Z.]+)?$/';, but that lead to another issue.

[naneau]

This is a change from SemVer version 1.0.0. I am going to introduce a new branch that is fully 2.0.0 compatible.

In fact, what I'll do is change master to 2.0.0 compat.