v0.1.30-pre.66

preview: the first page a newcomer reads now tells the truth on a computer. It said
"Messages are locked on your phone before they leave" on the desktop app and in a
browser as well as on a phone; it says "on this device", in English and every
translation that carried the phone. Wording only: no code, no behaviour and no schema
change, so it installs over anything in the 0.1.30 series either way.