DB: pass 'stat' to database objects
DB: read db_functions line per line
DB: add parts of db_functions when config is set
DB/Osmosis: enable multipolygon support (via osmosis-multipolygon)
DB/Osmosis: set tag 'osm:has_outer_tags' on multipolygons with outer tags
DB/Osmosis: when multipolygons are enabled, check outer areas

- Closed ways which are an outer member of a multipolygon which has outer
  polygons will not match 'area'.
DB/Osmosis: Document support of osmosis-multipolygon
DB/Osmosis: multipolygon relations will be removed from relations query

- also multipolygons with tags from outer members do not count as 'relation'
Merge pull request #64 from plepe/adaptable_db_functions

osmosis-pgsnapshot: support multipolygons via plepe/osmosis-multipolygon