Fixes cyclical dependency between dojox.gfx.d.ts and dojox.geo.d.ts

Removed reference to dojox.geo.d.ts (dojox.gfx has no actual dependency
on dojox.geo)
Removed sole reference to dojox.geo.openlayers.Point

Using dojox.gfx.Point instead, as in the rest of the file
Merge pull request #2959 from ca-ta/master

Fixes cyclical dependency between dojox.gfx.d.ts and dojox.geo.d.ts