onPassphraseFieldsModified now calls Fit() to ensure that the
message (e.g. "Passphrase is too short)" will not be truncated.

The message at the top of the dialog has been reformatted slightly,
so that the dialog's natural width is slightly larger, so that
the resizing of the dialog from onPassphraseFieldsModified is
not such a drastic change.
Fixed bug where onPassphraseFieldsModified was referring to
passphraseStatusLabel1 and passphraseStatusLabel2 which should have
been newPassphraseStatusLabel1 and newPassphraseStatusLabel2.

onPassphraseFieldsModified now calls Fit() to ensure that the
message (e.g. "Passphrase is too short)" will not be truncated.

The message at the top of the dialog has been reformatted slightly,
so that the dialog's natural width is slightly larger, so that
the resizing of the dialog from onPassphraseFieldsModified is
not such a drastic change.

Eliminated the hack of temporarily setting newPassphraseStatusLabel2
to its longest possible string, then calling Fit, and then setting it
back to a blank string.  This was designed to ensure that the dialog
was wide enough to contain the longest passphrase status messages,
but it didn't work reliably.

Removed message dialog saying "Passphrase updated successfully!"

Minor changes to onPassphraseFieldsModified, inspired by
CreateNewKeyDialog's onPassphraseFieldsModified.