merge and primitiveTransform now save their state for easier replay
Transformer no longer optimizes initialization when there are no observers yet

This make sure that the transformer function is tiggered initially so
that local state can be set if needed.
Removed Rx.JS as dependency
Added some utility code for easier logging / tracing
Fixed issue where Event.toString() could result in a json error
rewrote replay to be able to use 'this.out' to emit events, this makes the implementation of most replay functions simpler
Introduced FumeError. Improved cycle detection