Esri zoombounds

Did some manual checking for the zoom bounds of Esri layers:
<pre>
DeLorme:			1...11 (no 0 tile)
WorldTopoMap:		0...18
WorldImagery:		0...18 (some area's don't have 18)
WorldStreetMap:		0...18
WorldTerrain:		0...13 (in US area's, up to 9 in NL)
WorldShadedRelief:	0...13 (higher tile requests get a 404 response)
WorldPhysical:		0...8  (higher tile requests get a 404 response)
OceanBasemap:		0...13 (in US coastal area's up to 13, other area's up to 10/11)
NatGeoWorldMap:		0...16 (North america up to 16, NL up to 12.)
WorldGrayCanvas:	0...16 (NY has 16, + France/NL, Some other areas only up to 13)
</pre>