Modified Tile, TileRequest and calling web API functions to aim to enable
Difference calculations to be able to use different graphs for the
calculation.
Fixed an issue with TileRequest equality checking introduced in previous
commit on this branch (in case of null routerId2).
Fixed up an error in Analyst re checking routerId input to getSamples() in
Tile class implementations (due to recent changes).
Merge remote-tracking branch 'origin/allow-selection-graph-rest-wms-tile' into melbprod