The XML API for Geonames contains much more detailed error information
than the JSON one. So, I've converted this plugin to use it instead.
It seems to be the preferred format for Geonames, so biting the bullet
on this makes sense.
Caching support will be added in future work after unit tests have been added.
* extlib: add PEAR HTTP_Request2 0.4.1 alpha
* extlib: update PEAR Net_URL2 to 0.3.0 beta for HTTP_Request2 compatibility
* moved direct usage of CURL and file_get_contents to HTTPClient class, excluding external-sourced libraries
* adapted GeonamesPlugin for new HTTPResponse interface
Note some plugins haven't been fully tested yet.
