- Added callCheckMethod() for making easy the integration with   the PEAR_installer class - Reverted the logic of the returned value of the check methods.   They will return false on no error or the error string on error - Added signOperator() to output the representation of the operator   with signs instead of letters ('ge' -> '>=') - Other minor changes
- Added callCheckMethod() for making easy the integration with
  the PEAR_installer class
- Reverted the logic of the returned value of the check methods.
  They will return false on no error or the error string on error
- Added signOperator() to output the representation of the operator
  with signs instead of letters ('ge' -> '>=')
- Other minor changes


marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core,marcosptf/pear-core