TMS spec supports a tile origin other than 0,0 (see: http://wiki.osgeo.org/wiki/Tile_Map_Service_Specification ).  Building on previous work to make origin available to all within TileCacheLayerInfo, this update supports the tileOrigin param as expected in the spec (x,y) or as some clients report via lon, lat.
update the documentation for tms support of tileOrigin
Add resources for further exploration