Islandora Authority Module
  (Perhaps this module in particular should be renamed to something like 
  islandora_solr_autocomplete...  That's all it does at present.(

--- Description ---
  This module adds two elements (islandora_authority_{textfield,hidden}) and a 
menu-path used for autocompletion.

  The autocomplete path added is: 
islandora/authority/{form-buildID}/{current_elementhash}/{search} 
Do note that the build ID and element hash are put into the autocomplete path in 
islandora_authority_textfield_process, and the default autocomplete path for the
textfield elements is islandora/authority, so all we need are the fields in 
which to search, and so we go on to...

--- Configuration ---
(NOTE: all config info is stored in #user_data on the relevant elements)
  The basic setup is that multiple islandora_authority elements are direct 
children of a common parent; this greatly simplifies configuration, because only
have to look at a small part of the form.  
The parent currently has two parameters:
* islandora_authority_t_pattern:  A pattern as used by Drupal's t() function, 
  likely using variables.
* islandora_authority_fq: A list of tilde-separated Lucene statements, e.g.:
  PID:ir*, to ensure all results come from the IR namespace.
  (Note:  separating is (currently) done via a dumb explode; tildes in values
  break it)

Each contained authority element specifies:
* islandora_authority_solr_search_field: A EdgeNGram'd Solr field
* islandora_authority_solr_display_field: An optional Solr field, used for 
  display purposes  (defaults to the search field)
* islandora_authority_mapping: Optional, which is a 'variable' as used in 
  Drupal's t() function (subbed into the 't_pattern' in the pattern for each
  result)