* Fixed NaN on normalize 0 vector.
* Tentative implementation in getStepLength.
* mapEntity.TileX/Y removed.
* Fixed Position and Target not being initialised in createMapEntity.
* mapEntity.Position is no longer embedded.
* mapEntity.LocationX/Y no longer used outside map_entity.go.
* mapEntity.subCellX/Y removed.
* mapEntity.LocationX/Y removed.
* mapEntity.OffsetX/Y and TargetX/Y removed.
* Direction method added to Vector, returns 0-64 direction.
* Moved Vector.Direction() to Position.DirectionTo and refactored.
* Renamed RenderOffset from SubCell and tested IsZero.
* d2math.WrapInt added for use with directions.
* Tidied up position and tests.
* Refactored d2common.AdjustWithRemainder into d2mapEntity.
* Tidying up d2mapEntity.
* Final cleanup.
* Lint warnings.
* Spelling correction.
