Also adjusted continuous integration setup accordingly.

Get jetty to use system temporary folder when extracting war file rather than creating a directory in the Vufind root - comment out tempDirectory setting in /solr/jetty/contexts/solr.xml

* VuFindSearch/Backend/Solr/HandlerMap.php: New class. SOLR
  handler map.

* VuFindSearch/Backend/AbstractHandlerMap.php: Expect ParamBag as
  return value for D/A/I.

* VuFindSearch/ParamBag.php (params): Removed. Use getArrayCopy()
  instead.

* VuFindSearch/ParamBag.php (exchangeArray): Use internal function
  to set new parameter array.

* VuFindSearch/Backend/AbstractHandlerMap.php: New class. Abstract
  base class of handler maps.

* VuFindSearch/ParamBag.php (exchangeArray): New function. Exchange
  parameter array.

* VuFindSearch/Backend/Solr/Connector.php (MAX_GET_URL_LENGTH): Fix
docstring.

Expanded test suite to match.

Expanded test suite for writer.

Thanks to Arek Danszczyk and Christian Dabrowski.

* VuFindSearch/Backend/Exception/BackendException.php ($tags): New
  property. Tags.
  (addTag, getTags, hasTag): New functions. Tagging support.

* VuFindSearch/Service.php (search, retrieve,
  retrieveBatch) (similar): Catch BackendException, trigger error
  event & rethrow.

* VuFindSearch/Service.php (triggerError): New function. Trigger error
  event.

* VuFindSearch/Backend/Solr/Connector.php (resubmit, getLastQueryParameters,
  $lastQuery): Removed.
  (query): Remove usage of $lastQuery.

* VuFindSearch/Backend/Solr/Backend.php (aggregateSpellcheck): New
  function. Factored out from search().
  (search): Factored out aggregated spellcheck, use local boolean var to
  indicate spellcheck.

* VuFindSearch/Backend/Solr/Backend.php (search): Set offset and limit
  in parameter bag.
* VuFindSearch/Backend/Solr/Connector.php (search): Change function signature,
  offset and limit contained in parameter bag.

* VuFindSearch/ParamBag.php (contains): New function. Return true if bag contains a parameter-value-pair.

(Facet names with quotes or back slashes do not return results)

Thanks to Tom Misilo for the suggestion.

Created convenience method to forward to confirm action.
Improved some style issues.
Use route parameters rather than query parameters for cleaner data passing.
Thanks to Luke O'Sullivan for development assistance.