make it possible to ignore numZoomLevels when reading a WMC

[bartvde]

Comment by elemoine (2 options given to solve this):

I was hoping you could override options read from the WMC doc by
setting layerOptions in the WMC formation options, but applyDefaults
is used there so overriding isn't possible.

Or maybe layerToContext shouldn't set layer.numZoomLevels in the
context if layer.options.numZoomLevels is null.

[bartvde]

Also depends on ticket:2427

See this thread for more info:

http://openlayers.org/pipermail/dev/2010-April/005883.html