Move code out of apachesolr_search_search into separate functions

This patch is against current dev branch.

Moved code inside apachesolr_search_search() to
* apachesolr_search_params($query) which returns $params
* apachesolr_search_query($keys, $query, $params) which contains $solr->search() and returns $results;

So that when returning custom search results, can create a hook_apachesolr_modify_query with a custom caller (e.g. mytest_caller):

$keys = 'test';
$query = apachesolr_drupal_query($keys, 'type:blog');
if (is_null($query)) {
  throw new Exception(t('Could not construct a Solr query()'));
}       
$params = apachesolr_search_params($query);

apachesolr_modify_query($query, $params, 'mytest_caller');
if (!$query) {
  return array();
}
$results = apachesolr_search_query($keys, $query, $params);

Changed the function name from apachesolr_search_query to apachesolr_search_results for more clarity.

Moved $_GET variables to the top, and passed it to _apachesolr_search_search, such as $filters, $solrsort, $page.

So that when other modules would like to return results from apache solr module can call on
_apachesolr_search_search($keys, $filters, $solrsort, $page);

e.g.
$results = _apachesolr_search_search('test', 'type:blog', '', 3);

This patch, the function name is

function apachesolr_search_searchresults($keys, $filters = '', $solrsort = '', $page = 0, $caller = 'apachesolr_search')

How about hook_search calling one function which does some processing/validation and calls the 3 or 4 functions.

    case 'search':
      $filters = isset($_GET['filters']) ? $_GET['filters'] : '';
      $solrsort = isset($_GET['solrsort']) ? $_GET['solrsort'] : '';
      $page = isset($_GET['page']) ? $_GET['page'] : 0;

      return apachesolr_search_searchresults($keys, $filters, $solrsort, $page, 'apachesolr_search');

inside function apachesolr_search_searchresults() is the try/catch block with

    $solr = apachesolr_get_solr();
    $params = apachesolr_search_params_basic($query, $solr);
    apachesolr_search_add_facet_params($params, $query, $solr);
    apachesolr_search_add_boost_params($params, $query, $solr);

as well as apachesolr_drupal_query(), apachesolr_current_query(), apachesolr_modify_query(), $solr->search(), apachesolr_static_response_cache(), apachesolr_has_searched() and finally returning apachesolr_process_response()

On the note of all this moving around, as well how about the use of >module_load_include() to move the search code, which is only used on search pages out of the apachesolr_search.module file, to reduce the overall load to drupal pages.

Likely, the increase in performance of drupal will be minimal for this type of change in only one module, but it might add up with more modules.

Awesome Peter, thank you.

This really helps, as I had some people using the pre-dismax style of returning custom search results, by calling apachesolr_search_search('search', "keywords type:blog"), now can call apachesolr_search_execute('keywords', 'type:blog')

I am of the opinion that CS professors would be offended to learn that only ~1% or less of code being loaded into each and every page load is used. Possibly a couple of megabytes worth of memory could be freed up.

Functions that other modules are likely to use might make sense to be inside the .module file, otherwise there is no point imo.