License

The Flowable project is distributed under Apache license V2 unless for these exceptions:

We are including slightly modified source code of the Apache Licensed JUEL 2.2.1, created by Odysseus Software GmbH.

Documentation

Great community contribution for collapsed sub processes by David Pardo. You now can model processes in a hierarchical way without needing to use call activities, which result in different process definitions in the Flowable Engine. When using collapsed sub processes, the modeling part is hierarchical and using different model diagrams for the main process and the sub process models. But when deploying on the Flowable Engine, there's still one process definition using embedded sub processes. So this feature it targeted at the modeling level.
Bug fix for service tasks with class attributes using skip expressions.
Added support for using the Flowable namespace in addition to the Activiti namespace in BPMN XML.
Several bug fixes and smaller enhancements

First Flowable release. Except from the different Maven group (org.flowable) and artifact id (flowable-engine etc) no changes have been made to package names or config file names.
Introduction of transient variables. Transient variables won't be persisted in the Flowable variable tables, but are still available on the execution for the duration of a single transaction. Transient variables can for example be used to store a REST response that is only needed to create a request to another REST service, or to use a Java service task result in the next Java service task without it getting persisted. You can read more about it here
Several bug fixes and smaller enhancements