WMSProxy and Layer - POST requests support

[adube]

Short Description

• Add POST request support for WMS GetMap request in the WMSProxy.
• Set a maximum number of characters for WMS layers created by the Layer widget

Explanation

OpenLayers.Layer.WMS object support setting a parameter to limit the number of character allowed in a GET request. Past that number, the request becomes POST.

MapServer already support reading WMS POST requests. We only need to support it in the WMSProxy as well.

Issue example

The ApplyFilter widget uses a SLD_BODY parameter in the WMS GetMap request to filter the map displayed. Its content can become quite long if the layer definition in the mapfile has many CLASS objects, thus resulting in too large requests.

[adube]

Fixed in r1394.