Description
   Validate the running PEAR version against the dependency.  This dependency is designed
   to prevent PEAR versions incompatible with the current package.xml from attempting to install
   it.  As with all dependency validation, true is returned on success, PEAR_Error on failure
   for required dependencies (and the PEAR installer dependency is required).  If the
   soft, force or ignore-errors
   options are specified, an array containing the error message will be returned instead.