Name deduplication improvements

[MonkeyDo]

Problem

This PR addresses a few issues with name deduplication and other search-related mechanisms in the entity editor:

• BB-356: Editions with the same name should be allowed
• BB-413: Name deduplication triggers for the entity being edited
• BB-537: Don't auto-select matching Edition Group

Solution

1. Allow Editions and Edition Groups with the same name (without requiring a disambiguation)
2. Autocomplete and deduplication mechanisms should filter out the entity being edited from its results to avoid conflict with itself.
3. For an Edition with a name matching that of an Edition Group, instead of auto-selecting the first exact match, display a list of exact matches to allow the editor to select one, or opt for searching for another one or automatically creating one; once an EG is selected, hide the list of matches:

Here a match is shown, but not selected yet, and an EG will be created automatically.

Here the editor chose to search for an existing one and can select one or choose to revert to auto-creation.

Here the exact match was selected. If any EG is selected, we hide the list of matches (we don't want to confuse editors with a warning-colour thing when everything is all right)

Areas of Impact

EntityEditor component, mainly EditionSection and NameSection.

[coveralls]

Coverage increased (+0.01%) to 60.851% when pulling 1831eeb on dont-deduplicate-editions into 55ff508 on master.