Remove DataObject interfaces and focus on pages

[stevie-mayhew]

cc @wernerkrauss

I'm looking at removing the DataObject parts of this system completely as we don't tend to use them, and there are other options for this.

Thoughts?

[stevie-mayhew]

cc @Olliepop

[wernerkrauss]

It should still be possible, to manage Dataobjects in the same ModelAdmin / CatalogueAdmin together with pages. E.g. if i want to manage Products (a page) and ProductCategories (Dataobjects) in a Modeladmin.

[stevie-mayhew]

Fair point, for now I'll tolerate them. Would you be opposed to it being in its own repo which requires this one?

[wernerkrauss]

As https://github.com/Little-Giant/silverstripe-catalogmanager/blob/master/code/ModelAdmin/CatalogPageAdmin.php#L20 checks for existence of the extension on the managed DataObject or Page it should be possible to remove it as it degrades gracefully to ModelAdmin. Haven't used it myself in the last project.