OpenLayers.Control.WMSGetFeatureInfo should support the POST request method

[neumann]

For a long list of layers with long layer names it is possible that one hits a URL length limitation in IE6 to IE8 with the GET request. The problem is that the WMSGetFeatureInfo Request often fully repeats the layer list, once in the LAYERS parameter and once in the QUERY_LAYERS parameter. See  http://support.microsoft.com/kb/208427 for the URL length limitation.

To work around the problem I suggest to introduce a new requestMethod parameter in OpenLayers.Control.WMSGetFeatureInfo which allows to use a POST instead of a GET request. Of course the WMS server would have to support POST as well. I checked with mine (QGIS server) and it will support POST requests soon.