Simplify content group model for content publishing
This introduces a new publishing mode with a single index which replace the published state and publishing range.
Value for publishingMode:
- NONE: Publish no contents / do not publish content group at all
- ALL: Publish all contents
- SINGLE: Publish a single content
- UP_TO: Publish contents up to index
The model for statistics has been adjusted to reflect this change and now includes the count of content groups by mode instead of the count of published ones and those using publishing range.
Closes: #236 (closed), #237 (closed)
Edited  by Daniel Gerhardt