[WMS-WFS-WCS] Unify use of *_name metadata

[dmorissette]

We need to unify the use of the xxx_name metadata by the WMS, WFS and WCS server
and client interfaces.  At the moment we have the following situations:

WMS Server:
  - Uses layer->name to set layer <Name> in Capabilities
WMS Client:
  - Uses wms_name for the LAYERS=... parameter in GetMap request

WFS Server:
  - Uses layer->name to set layer <Name> in Capabilities
WFS Client:
  - Uses wfs_typename for the TYPENAME=...parameter in GetMap requests

WCS Server:
  - Tries in the following order: wcs_name, ows_name, wms_name, or layer->name
    for the <Name> in Capabilities


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I propose that we unify by doing the following changes:

WCS Server stays as is.

WMS server Capabilities (layer <Name> element):
  - Lookup wms_name, ows_name, and layer->name in this order
    ... no big deal, this is just adding a lookup of Metadata
    in priority over layer->name, so that won't break anything

WMS client:
  - no change

WFS server Capabilities (layer <Name> element):
  - Lookup wfs_name, ows_name, and layer->name in this order
    ... once again this won't break any existinng mapfile

WFS Client:
  That's where things break:
  - For the TYPENAME=... parameter, lookup "wfs_name" instead of "wfs_typename"
  ...perhaps we could just deprecate "wfs_typename" and continue to support
     it for a few releases, but "wfs_name" is really what we should use and
     should be officially documented.

[dmorissette]

Not in 4.4, hopefully in 4.6