lyx2lyx for InsetLayout Argument

[Julien Rioux]

In 2.1 if I define Arguments for my InsetLayout (great feature!) I note 
that lyx2lyx backport from 2.1 to 2.0 converts

\begin_layout Argument 1
to

\begin_layout Argument

which isn't understood by 2.0 (maybe this conversion works for Style, 
which has some OptArgument and ReqArgument support already in 2.0, but 
InsetLayout doesn't have this support).

Known issue?

--
Julien