General purpose getCorner function for extents
Function for creating tile grids from extents
Respect XYZ source projection
Sources may be configured with a projection, tile grids with an extent

An XYZ tile grid is constructed with an extent defining the bounds of the tile grid.
Respect the tileSize option for XYZ grids
Additional documentation
Merge pull request #1124 from tschaub/xyz

Allow tilegrid creation from projection or extent.