version to 0.3.0

* redesign: adding IO to cmds (#35)
* redesign: reworked cache cmd to use the new stuff and to match digest cmd (#34)
* redesign: tweak digest cmd implementation to always use active state (#32)
* Redesigned `digest` cmd (#31)
* redesign: source file `digest` method (#30)
* Switch to using `config.output_path` instead of deprecated `files_path (#29)
* source file handler (#28)
* redesign: compile Engine definition and registration API (#27)
* redesign: digests model (#26)
* redesign: read source list on init (#24)
* redesign: configuration updates to support full digesting (#23)
* Some tweaks based on real usage (#22)