Renamed some columns to be more generic and applicable.
Removed now redundant book_id column.
Allowed nullable entity morph columns for non-entity activity.
Ran tests and made required changes.
Repos are generally better since otherwise we end up duplicating
things between front-end and API.
Types moved to by CONST values within a class for better visibilty
of usage and listing of types.
- Also aligned format of command descriptions.
Targeted most common columns.
Have not done revisions for the sake of keeping that
content true to how it was originally stored but could
cause unexpected behaviour.
For #1225
* Started mass-refactoring of the current entity repos
* Rewrote book tree logic
- Now does two simple queries instead of one really complex one.
- Extracted logic into its own class.
- Remove model-level akward union field listing.
- Logic now more readable than being large separate query and
compilation functions.
* Extracted and split book sort logic
* Finished up Book controller/repo organisation
* Refactored bookshelves controllers and repo parts
* Fixed issues found via phpunit
* Refactored Chapter controller
* Updated Chapter export controller
* Started Page controller/repo refactor
* Refactored another chunk of PageController
* Completed initial pagecontroller refactor pass
* Fixed tests and continued reduction of old repos
* Removed old page remove and further reduced entity repo
* Removed old entity repo, split out page controller
* Ran phpcbf and split out some page content methods
* Tidied up some EntityProvider elements
* Fixed issued caused by viewservice change
Added testing to cover each command.
Removed example laravel inspire command.
Standardised command names to be behind 'bookstack' naming.
In reference to #320.
