apachesolr 6.x-1.0-beta6

#305370 by pwolanin, Handle failed delete requests so unpublished/deleted content doesn't stay in the index.
#407570 by pwolanin and moshe weitzman, _alter for sort links, hide for < 2 results.
#392978 by pwolanin and ncameron, workaround for those using php 5.1, update README.
#402984 by JacobSingh and pwolanin, put MLT menu under the general ApacheSolr settings.
#401442 by Janusman and pwolanin, no sort block when 0 results.
#405732 by JacobSingh, pwolanin: Update to new SolrPhpClient (r6) and make ping() use drupal_http_request.
#405722 by JacobSingh, increase ping timeout and make it variable.
#400882 by mkalkbrenner, fix faceting bug due to static counter in method add_field.
#382358 by pwolanin, use tokenizer solr.CharStreamAwareWhitespaceTokenizerFactory to fix highlighting.