New element selector configuration dialog

New element selector configuration dialog

Includes element type selection and property selection from drop-down
menus. Also includes some refactoring of the underlying selector code.

gitlab #84

Change-Id: If5e42a7962d6d17b97a9fb6a3d207ed860858b8c

Remove block of commented-out code

gitlab #84

Change-Id: Ia75eeb9e9a2a4dc5a339244837cd6e6f01f97891

Layout adjustments in element selector dialog.

gitlab #84

Change-Id: I28de9ca5e1bc22eef607126ec75dcd3a93263188

More rigorous content validation for element selection dialog

gitlab #84

Change-Id: Iadb875ea9db3db8350095e21c39ecfad6cc6af36

Remove misplaced pop-up menu command

gitlab #84

Change-Id: I4412390556daacc4172c34018fa9d0fea65bf586

Rename element selection view in UI to "District Finder"

gitlab #84

Change-Id: I668eb468c169ccd8dfd8575daff9c1f1a0f01f2d

Manage drop-down menu contents by context in district finder dialog

gitlab #84

Also fix failure in creation of new queries.

Change-Id: I122ec005119a7efd8878b24815dc09a226e8b6d9

Fix use of static ontology variables out of context

gitlab #84

Change-Id: I94d17685f44e4bbfdaccaf9b3bfabefacb4e1c8e

Fix validation of selection by property when not used

gitlab #84

Change-Id: I6fd1b5d297ac2a07536edcd51a5f1b1099e3d06d