Fix validation warnings (gaps, etc) for bus routes in Singapore, pt2

Fix a few validation warnings (gaps, etc) for bus routes in Singapore

Add wikimedia_commons picture to a khachkar in Dilijan

Map a bench in Sarajevo

Fix PTv2 for London Buses route 16 → Brent Park, Superstores

Update tags for three post boxes in Viciebsk

Survey three post boxes in Viciebsk

Survey six more post boxes in Viciebsk

Add wikidata tags to two post boxes in Viciebsk

Survey another post box in Viciebsk

Survey a post box in Viciebsk

Survey post boxes around Llandudno

Survey three post boxes in Jersey

Fix PTv2 for London Buses route 276

Survey the post box W8 5D

Survey a post box near Swiss Cottage

Survey a post box in Aldwick

Survey a post box in Bletchley

Survey a post box SW1E 43

Survey post boxes in BS 25--27