SF #498254, fix implicit returns
SF #498254, fix implicit returns

Cleanup a lot of old code which only half worked:
  * Fix check for implicit return, return the line in err as the last line + 1
  * Remove _implicitReturnUnreachable(), it's not necessary
  * Remove code to try to remove implicit returns (2 places)

Other cleanup:
  * Stop using code.returns, it was removed b/c it was redundant
  * Create a function for _checkUnusedParam()
  * Create a function for _findUnreachableCode()
      FIXME: still need to impl a new warning for unreachable code
             this was just a utility for finding implicit return values
  * Add FIXME about im_class issue in Python 2.2 for finding base class name

thomasvs/pychecker,akaihola/PyChecker,akaihola/PyChecker,thomasvs/pychecker