Update to 2.53.3

The database format of the stored passwords and certificates in the user profile are now changed. SeaMonkey should perform the changes hiddenly at the first run, just asking for the master password (if used). To avoid a hypothetical data loss, it is recommended to backup user profile before the update, or even drop master password temporary. After the change, new files cert9.db and key4.db shoud appear in the user profile. (The old ones, cert8.db and key3.db, might be preserved as well, but make sure they are not leaved unencrypted if you use master password).