Catch-all for a number of VelocityResponseWriter cleanups/improvements for 5.0:
- CSS overhaul needed. Color scheme change. Add styling for <em> tags so highlighting stands out better.
- Look up uniqueKey field name (for use by highlighting, explain, and other response extras)
- spurious velocity.log's => route to logging to Solr's logging facility
- Add back Velocity file resource loader, off by default. Set template.base.dir writer init param to enable. This was in pre-
SOLR-4882(4.6), enabled by a request-time v.base_dir parameter. Current implementation is enabled by an init-time parameter if specified and exists
- Make params resource loader optional, off by default. Set params.resource.loader.enabled=true to enable.
- Make solr resource loader optional, on by default. Set solr.resource.loader.enabled=false to disable.
- Allow custom Velocity engine init properties to load from custom file: init.properties.file (formerly there was v.properties request-time)
- can go to town with trickery from http://velocity.apache.org/engine/devel/developer-guide.html#Velocity_Configuration_Keys_and_Values
- Allow layout to be disabled, even if v.layout is set; use v.layout.enabled=false to disable layout (request-time)
- Added $debug to context (it's just QueryResponse#getDebugMap()); makes it easy to #if($debug)...#end
- Improve macros facility, put macros in your macros.vm. (with legacy support for VM_global_library.vm)