Page Turner search-in-a-page solr configuration

Pretty straightforward solr configuration used for ptsearch.

See branch solr-tomcat for the pre-solr8 configuration.

Always use wt=xml

The cilent code expects XML responses; thus in the solr8 branch the search handler needs to have that set as a default, since more modern solrs default to json.

Highlighting

The pt code expect hl.tag.pre and hl.tag.post to use {lt:} and {gt:} instead of < and >, as see in the solrconfig.xml file.