Opensearch / fix & improvements

[fxp]

Patch provided by Oscar Fonts

• Added the 'geo' xml namespace, mandatory for a 'valid' document.
• Shortened the ShortName tag. Added a LongName tag.
• Changed url mime type to "application/rss+xml", as it is the response format for rss.search service.
• Added a second url with type="text/html" whose searches go through main.search service. And made that service available to guest user. That means that Firefox/IE will show HTML resultsets instead of rss, much more human-readable.
• Added geometry, name, and hitsPerPage request parameters.
• Changed favicon mime type to "image/x-icon", more standard.

See ​http://n2.nabble.com/OpenSearch-geo-td4542492.html#a4542492

[fxp]

Committed revision 5793.