Add equals/hashCode to APIs, and deprecate groupBy.
Add equals/hashCode to APIs, and deprecate groupBy.

equals/hashCode are useful for debugging/verifying/testing,
and the groupBy implementation is naive. It'll be replaced
by a groupBy implementation in Analysis that will handle
external/internal dep transitions correction.

jaceklaskowski/sbt,xeno-by/old-scalameta-sbt,corespring/sbt,sbt/sbt,mdedetrich/sbt,sbt/sbt,xeno-by/old-scalameta-sbt,dansanduleac/sbt,dyx/sbt,jaceklaskowski/sbt,mdedetrich/sbt,Duhemm/sbt,xuwei-k/xsbt,jkinkead/sbt,sbt/sbt,twitter-forks/sbt,mdedetrich/sbt,xeno-by/old-scalameta-sbt,Duhemm/sbt,dyx/sbt,mdedetrich/sbt,twitter-forks/sbt,jaceklaskowski/sbt,sbt/sbt,mdedetrich/sbt,som-snytt/xsbt,xuwei-k/xsbt,dyx/sbt,xeno-by/old-scalameta-sbt,dyx/sbt,jaceklaskowski/sbt,adriaanm/sbt,jkinkead/sbt,jkinkead/sbt,xeno-by/old-scalameta-sbt,pdalpra/sbt,Duhemm/compiler-bridge,twitter-forks/sbt,twitter-forks/sbt,mdedetrich/sbt,mdedetrich/sbt,jaceklaskowski/sbt,xuwei-k/xsbt,jkinkead/sbt,dyx/sbt,twitter-forks/sbt,pocketberserker/sbt,jasonchaffee/sbt,sbt/sbt,xuwei-k/xsbt,sbt/sbt,xeno-by/old-scalameta-sbt,xuwei-k/xsbt,sbt/sbt,Sciss/sbt,jkinkead/sbt