Split off & rename project to semver4j.
Use Objects.requireNonNull.
Migrate from sbt to Maven, so I can use pitest (& therefore other tools).
conf: Sort suppressions by files intead of by checks.
conf/checkstyle-suppressions.xml: Suppress checking funky test method names.
test: Add UtilsTest, also for pitest.
SemVer: Make groupingRegex private (why was it public? :S).
test/SemVerTest: Inline a few statements.
SemVer: Add a matches(String): boolean method & use it in tests.
SemVer: Make matchingRegex: Pattern private as well (WTF).
build: Make jsr305 scope=test instead of optional=true as it's only used in tests (via guava).