Change the echo status to OFF on each example execution. This helps to
reduce the need of an active echo-filtering at the expense of some
additional overhead.

Because this could break users' examples (very unlikely), we set this to
False by default (no turn off is done) and we delay the default to True
(turn the echo off) for byexample 11.0.0

…ch-Exec-for-10.5.4

Issue 245 turn echo off on each exec for 10.5.4