Actress merge

continuation of #72, needs more work and discussions
- [x] change Abstract class to module
- [x] remove Algebrick dependency
- [x] remove Atomic dependency
- [ ] cleanup
- [ ] split-files
- [ ] documentation
- [ ] add example of using Actors with Algebrick
- [ ] there are intermittent concurrency errors, run test-suite 100x or so to find them
- [ ] tests
- [ ] check all TODOs left in the code

**Then**
- [ ] basic supervision and restarts
- [ ] actor state monitoring as in Akka

**Later**
- [ ] un/become ?
- [ ] dead letter routing ?