apachesolr 6.x-1.6

Changes since 6.x-1.5:

• #1097976 by Nick_vhy: Fixed wt=xml for Solr 3.x compatibility when viewing admin files.
• #1309252 by kevin.dutra, lazysoundsystem | gateway69: Fixed Undefined Index: ts_vid_names() in Apache_Solr.
• #901376 by LiuShaz: insure UTF-8 encoding is used for POST searches.
• #1224748 by pwolanin, David Lesieur: fix nodeapi params.
• #1224748 by pwolanin: prevent fatal error on hook cron by omitting nodeapi params.
• #1188824 by craig_: skip apachesolr_cron if in read-only mode.
• #1186830 by jp.stacey: db_rewrite_sql on term_hierarchy can lead to invalid SQL.