FIX: "pyFtp": Stringify handles; return result in "close()".
CHG: "pyFtp.fail()": Include error message and error type in result.
ADD: "pyFtp": Add "closeAll()" and "errorString()".
ADD: "pyFtp": Add "chdir()" and "mkdir()".
ADD: "pyFtp": Add comment on the purpose of "self.openFiles".
CHG: "pyFtp": Separate creation and connection for easier handling in JS.