Documentation 
This function is used in the tag editor's autocompletion textboxlist to return
a set of matching tags given the prefix in the url param 
q. See the 
classificationplugin.tmpl template
file. This in essence is functionally equivalent to 
RenderKnownTags however is using 
SolrPlugin
if installed for better performance.
  Parameters 
 
-  TAG: pattern of tags to include, defaults to a neutral filter; this pattern is to match the prefix of the tag name
-  LIMIT: maximum number of categories to return, defaults to 10
-  THEWEB: web from which to extract category information, defaults to BASEWEB
  Implementation 
%STARTINCLUDE%%SOLRSEARCH{
  web="%THEWEB{default="%BASEWEB%"}%"
  facetlimit="tag=%LIMIT{default="10"}%"
  field="none"
  facets="tag"
  facetprefix="%TAG{default=""}%"
  facetsort="index"
  header_tag="[$n"
  format_tag="{\"value\":\"$key\"}"
  separator_tag=",$n"
  footer_tag="$n]"
}%%STOPINCLUDE%
  Test 
[
{"value":"BarBaz"},
{"value":"FooBar"},
{"value":"a a a"},
{"value":"fertig"},
{"value":"festival"},
{"value":"freak"},
{"value":"test"},
{"value":"topic"}
]