Tidy was only being used by a couple of non-default URL shortener plugins,
PtitUrl and TightUrl. Both were easily changed to load the tag-soup HTML
via DOMDocument (using the default DOM module which is already used by
other dependencies).
Added xml, dom, and simplexml modules to the requirements check
in install.php, as they were being used but not checked for.
Also cleaned up LilUrl, PtitUrl, and TightUrl to return URL as a string
instead of as a SimpleXML node object.
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.
