Re-add the QScriptEngine::addTranslatorFunctions API that brings back
qsTr() and friends to pure QJSEngine based environments.
The auto-test were also ported where applicable.
Change-Id: Ib03e3495ef09eeea9e4c8341061499768caed307
Sanity-Review: Simon Hausmann <simon.hausmann@digia.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>