CRM-12638 cache search count

----------------------------------------
* CRM-12638: Optimize Prev/Next Cache and search interaction
  http://issues.civicrm.org/jira/browse/CRM-12638
Cleanup
CRM-12638 only rebuild alpha pager when needed

----------------------------------------
* CRM-12638: Optimize Prev/Next Cache and search interaction
  http://issues.civicrm.org/jira/browse/CRM-12638
CRM-12638 Optimize filling prevNext cache and displaying results

----------------------------------------
* CRM-12638: Optimize Prev/Next Cache and search interaction
  http://issues.civicrm.org/jira/browse/CRM-12638