Editor / Distribution / Display gmd:linkage instead of gmd:URL

[fxp]

Currently, in default view mode, the gmd:URL is displayed in the editor and not its parent (ie.gmd:linkage).

<gmd:linkage>		  
  <gmd:URL>http://www.ifremer.fr/services/wms/charm3</gmd:URL>							</gmd:linkage>

In order to be consistent with other ISO elements, I would suggest to consider gmd:URL like gco:CharacterString, gco:Angle, ... and display its parent as the main element in the editor.

An advantage of this, is that editors could easily edit extra attribute (like gco:nilReason) which are attached to gmd:linkage and not gmd:URL.

See patch attached.