Purge out :echoe

`:echoe` is unstable: unless it is already in `:try`…`:catch` block
you never know for sure whether or not it will break execution.
Thus the only valid use for `:echoe` is

    try
        echoe 'Msg'
    endtry
: rough equivalent to `:throw` (throws, but with different message).
As this is probably not the thing you want to do
I changed it to use `:echomsg`.