Add spatial search from KG

bugfix: aot build error

feat: new toast behaviour

fix region selector size issue
fix close / min btn translateY issue
fix splash screen showing header issue

refactor: use relatedAreas 

bugfix: preview area 44 receptor data

chore: restore animation to navigate to region

bugfix: singleDataset

feat: encodding region selected as b64, greatly reduce url lengtth

Feat: allow files listed by KG to be downloaded by the download btn

bugfix: include material css for local dev

chore: reworked reference component

chore: update testing for dropdown component

feat: implemented tests for encoding/decoding

comparison allen v3, ~580 regions selected:
- pre 2019 May release: 2854 char
- post 2019 May release: 7390 char
- this patch: 1997 char

maintaining backwards compat