we do the backup compression/writing in a separate thread so it
doesn't slow down profile switching/syncing, and remove the option
to write uncompressed backups
the strip html option is no longer used, so remove it from preferences
avoided adding this in the past as on a multi user system it allows
one profile user to annoys others by changing the interface language,
but it comes at the expense of easily changing the language for users
who choose the wrong one on first startup
