0.2-SNAPSHOT Added RefOne, RefMany, RefTraversableOnce, cross-compiling

Ref now implements TraversableOnce.  There are marker traits RefOne and
RefMany, to disambiguate that we now also have RefTraversableOnce that
can take a collection of items. Removed the external pom, updated sbt
to 0.12.1, and added settings to cross-compile to 2.9.1, 2.9.2, and
2.10.0-RC2
Experimental reworking

There's a lot of tinkering gone into this changeset, so it's hard to
provide a concise description.

Ref.gettId should no longer require reflection, but uses implicits to
be typesafe.

Ref.flatMap allows some subclasses to narrow the return type to R[B]
(the return type of the function passed in)

The TraversableOnce trait has been moved down to ResolvedRef rather
than Ref, as it may be hard for some Refs (such as an asynchronous
RefEnumerator) to implement
Added Approval

Added Approval.  This is intended to be a replacement for the
PermissionToken functionality, using Ref, flatMap, etc
Tweaks to implicit conversions

Started using the "extends AnyVal" notation from Scala 2.10's value
classes.
Added test for RefTraversableOnce
Partial. Added RefFuture, but it needs a few things fixing.
Added toRef for Future[T] and a few basic tests for RefFuture
Partial commit

A partial commit before I try something. NOTE: This intermediate
partial commit does not compile.
Partial commit

This compiles, but flatMap is problematic as RCFMT[Ref, ...] can't be
specialised to RCFMT[RefFuture, ...] in subtypes.
Updated README, now in Markdown.
Updated sbt version to 0.12.2