Fix for SI-6600, regression with ScalaNumber.

[paulp]

Not much in the end; I divided ScalaNumericConversions
into two traits such that the ScalaNumericAnyConversions can
be used in value classes, and ScalaNumericConversions can
override methods in ScalaNumber (since one trait cannot do
both those things.)

The fact that ScalaNumber is privileged for equality but a) extends
java.lang.Number and therefore b) cannot be a value class is something
we will want to revisit real soon.

[paulp]

Review by @jsuereth

[scala-jenkins]

jenkins job pr-scala-testsuite-linux-opt: Success - https://scala-webapps.epfl.ch/jenkins/job/pr-scala-testsuite-linux-opt/1538/

[scala-jenkins]

Started jenkins job pr-rangepos at https://scala-webapps.epfl.ch/jenkins/job/pr-rangepos/830/

[scala-jenkins]

jenkins job pr-rangepos: Success - https://scala-webapps.epfl.ch/jenkins/job/pr-rangepos/830/

[jsuereth]

Lgtm and absolutely correct on revisiting in the future.

[baloo]

This commit actually breaks compatibility between anyversion << 2.10-rc2 and 2.10-rc2. People may see errors like:

java.lang.NoClassDefFoundError: scala/math/ScalaNumericAnyConversions

while loading libs in rc2 in rc1 code.

This dependency on ScalaNumericAnyConversions is required as long as you use RichLong, RichInt, ... (see all subclasses of ScalaNumericAnyConversions) which may appear easily as they are implicits converting to them in Predef.

(I'm putting a comment so people may find answer on google.)

[paulp]

I imagine I'll have to repeat this a lot, but nobody should ever have expected binary compatibility between milestone and rc revisions of scala and the final release. We couldn't maintain it if we wanted to, not and actually fix things, which is kind of the point of releases before the final release. I'm sorry that sbt has a different idea about how things work.

[baloo]

Yes, it's just i've spent 6 hours debugging it, to finally find my lib was compiled against rc2 while i was using rc1 in my main app. As said, it was more to put this info in google.

[paulp]

Rest assured I sympathize wholeheartedly. https://groups.google.com/d/msg/simple-build-tool/d_Kd6H_QMmM/4ixXdxIUCvMJ