Re-examine whether the name derived for an automatic module can end in a digit

Automatic should have sensible, version-free names. As things stand then the module name derived for a JAR file named "guava19.jar" is "guava19". This issue tracks a re-examination of the derivation to see whether it would make sense to drop any trailing group of dots and digits (as in "(\\.|\\d)*$" ). Any changes in this areas will require coordination with javac, tests, etc.