This change allows for easy customisation of the relation manager titles and toolbar buttons.
For buttons - define your custom strings directly in the standard `toolbarButtons` syntax...
```
toolbarButtons:
create: acme.blog::lang.subcategory.CreateButtonText
delete: # omit the string to fall back to the default button text
```
...and the old syntax still works...
```
toolbarButtons: create|delete
```
For titles - define different strings for each mode (form, list or pivot)...
```
title:
form: acme.blog::lang.subcategory.FormTitle
list: acme.blog::lang.subcategory.ListTitle
```
This feature provides developer convenience, for example in this situation where I have a relation manager that is used to assign user permissions to a project:
Before
After
This PR contains no breaking changes.
Dan Harrin
Tschallacka
Samuel Georges
