Add utilities for running commands in stages (#140)

* Add more comprehensive test for context propagation in redirect

* Add tests for forking and exceptional execution

* Add test for redirect+execute nodes

* Cleanup some warnings from CommandDispatcherTest

* Remove leftover check (was needed when redirect was not cached)

* Refactor command execution loop and change "no command" behavior to not
depend on runtime

* Add utilities for running command chains manually

* Bump version

gradle.properties

@@ -1 +1 @@
-majorMinor: 1.1
+majorMinor: 1.2