Added support for calling JS functions in JSObject.
Added more conversions to JS objects.

Including functions up to Function2.
Moved BoxedUnit.scala to library-aux/

Because it is awkward to compile it with the rest of the lib.
Added a very rough sbt build for all the libraries.

The whole thing can be compiled with the 'compile-js'
task in sbt, and packaged into aggregated files with
'package-js'.
Ignore Eclipse files in subdirectories too.
Added a top-level package-js sbt task.