[WM] Deferr and get_current_main_content()

[jlm17]

> I think you can do:
>   $[some_perl_generated_content]
> instead of:
>   ${some_perl_generated_content}
> Note the square brackets for that "deferred content" effect.

Great this works. I didn't know I needed to do this in the <out> tag. The navtree documentation 
doesn't even say that you need to do this. Additionally looking at NavTree.pm I see this.

# just create a content item which calls our function below.
# we need to use a content item, so that it can be called
# deferred.

So this lead me to believe that the <navtree> tag is somehow internally deferring itself and that I 
don't need to do anything additionally. But you've set me straight.

Thanks again.