Code cleanup
CRM-12638 Fill prevNext cache only as needed

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

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* 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

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* 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

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

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* CRM-12638: Optimize Prev/Next Cache and search interaction
  http://issues.civicrm.org/jira/browse/CRM-12638
Merge pull request #1105 from colemanw/prevNext

Search optimizations: prevnext cache improvements