don't throw a MatchError on `SCALA_210 compare SCALA_28_29`

I encountered this when using today's Eclipse build (scalariform 0.1.2.201204270551):
Problems occurred when invoking code from plug-in: "org.eclipse.search".
scala.MatchError: SCALA_210 (of class scalariform.SCALA_210$)
	at scalariform.ScalaVersionGroup$class.compare(ScalaVersions.scala:11)
	at scalariform.SCALA_210$.compare(ScalaVersions.scala:20)
	at scalariform.SCALA_210$.compare(ScalaVersions.scala:20)
	at scala.math.Ordered$class.$greater$eq(Ordered.scala:86)
	at scalariform.SCALA_210$.$greater$eq(ScalaVersions.scala:20)
	at scalariform.lexer.ScalaOnlyLexer$class.getNumber(ScalaOnlyLexer.scala:468)
Merge pull request #48 from adriaanm/patch-1

don't throw a MatchError on `SCALA_210 compare SCALA_28_29`
Parser sync with scalac
Support extra type application syntax forms; fix AST display in UI
Tidy up and add a couple of extra type param tests
val P(a, b * c) = ... handling
Add separate command-line project
wip command-line tool
Add eclipse sbt plug-in
Format with sbtscalariform
stdin stdout options for CLI
cli tweaks
Run formatter
Fix AST selection for prefix expressions
rename subproject
Consolidate projects
Fix xml _* pattern parsing
Remove duplicate class
Add --quiet option to replace --verbose
Fix parser crash on malformed input