set up stubs for Scala Observable and its testing
add methods to Scala Wrapper (1)
add methods to Scala Wrapper (2) and find scalac bug
work around scalac bug by removing `extends AnyVal`
work around scalac bug by giving explicit type parameter to Observable constructor
add methods to Scala Wrapper (3) and find interesting questions

They are marked with TODO
add methods to Scala Wrapper (4)
Merge branch 'master' of github.com:Netflix/RxJava into idiomaticscala
add methods to Scala Wrapper (5) (window)
add Observer wrapper to make subscribe(Observer[T]) work
Merge branch 'master' of github.com:Netflix/RxJava into idiomaticscala
get rid of wrapper around Observer
add methods to Scala Wrapper (6)

includes typesafe dematerialize
make dematerialize infer everything
add methods to Scala Wrapper (7)
(does not compile!) refactoring of package structure

Compiles in eclipse, but not with gradle, because there
are package objects and packages with the same name.
refactoring package structure
Java example using Scala Observable code
IntervalDemo
add usability tests