Use Apache Solr 4.7.1
Use Apache Tomcat 7.0.53
Use Varien_Object for Facet and FacetOption models
Add methods to build add/remove filter URLs
Use Magento dl/dt/dd layered navigation markup structure
Detect multi-value fields from attribute property is_configurable
Use attribute to field name map
Add facet.mincount = 1
Link facet labels