Changes the directory on the FTP server you are logged in. The parameter can either be
an absolute path (e.g. '/home/mydir') or a relative one (e.g. 'mydir').
Parameter
string $directory - The directory you want to change to. This can
either be an absolute path (e.g. '/home/mydir') or a relative one (e.g. 'mydir').
Return value
mixed - true on success, otherwise PEAR::Error.
Throws
The returned PEAR_Error object in case of an error
is unspecific. You can ignore the errornumber and errormessage,
because only "Directory change failed" will be returned if the
operation fails.
