There are many API messages in Echo, so to make it easier
for translators, they are now in a separate group.
This is similar in Flow.
Must be merged along with the translatewiki change at
Iecedfe4cb9dc8e62a446a3e1c415a79e116ca27e
Change-Id: I1d3baea708107a7f15bf19671f7386eaf7e33a1b