DCP-o-matic 2.18.20 released

[carl]

Download now from here.

• Fix decryption of encrypted MPEG2 DCPs.
• Fix truncation of project names containing underscores.
• Always allow problem reporting, even when there's no loaded project.
• Make sure an email address is entered in the problem report dialogue before OK is enabled.
• Updated cs_CZ translation from Tomáš Begeni.
• Updated ru_RU translation from Евгений Дац.