CRM-14096 add check for civicrm-core dir in layout
CRM-14142 - 'Last modified' in Views

Adds the 'last modified' date of a contact to the Views integration: as
a field and sortable filter.
fixes for CRM-12956, bug in calculating custom field id

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* CRM-12956: CiviCRM custom fields (with selects) in Views are a mess
  http://issues.civicrm.org/jira/browse/CRM-12956
fix function getOperationPair - not static in parent class