Changed the {% editregion %} template tag, and introduced {% get_editregion %}
- {% editregion %} format is not {% editregion "REGION" obj <inherit> %}FALLBACK DATA WHEN NO CHUNKS FOUND{% endeditregion %}
- {% get_editregion "REGION" obj <inherit> as OUTVAR %} creates a new context variable with the chunk data and rendered output (`index`, `chunk` and `output` are available via dot notation)
Haven't fixed any tests that may've broken.
split the applabel/modelname discovery into it's own namedtuple subclass, as it'll make for easier debugging.