* split several source files
* move base settings sources (Scope, Structure, ...) into main/settings/
* breaks cycles. In particular, setting system moved from Project to Def
- interrupts task execution only
- no further tasks scheduled
- existing tasks interrupted
- a task must terminate any other started threads when interrupted
- set cancelable to true to enable
- currently, 'run' properly terminates if the application properly
terminates when interrupted
- 'console' does not, 'test' depends on the test framework
- also bundled: set connectInput to true to connect standard input to forked run
* Allow tasks to provide State transformations that are applied after all tasks complete.
* Provide convenience methods for preserving state across invocations.
* Option of session or persisted state.