Display relation memberships in inspector

* Preset icon of relation
* Preset name of relation
* Name of relation
* Member role
* Delete button

All currently unstyled.
Add common relation presets

Multipolygon is not included because multipolygon relations
should be matched by other presets.
Rename removeMember -> removeMembersWithID
Add iD.actions.DeleteMember
Hook up delete member button
Link to select relation
Hook up role input
Update memberships on change
Show editor for tagless member entities
Show relation members
Rationalize class names
Null check