include_block

Hi,

I'd like to propose a block tag `include_block'.  It would work just
like `include', but would additionally bind contents of the block to
some reasonable name, e.g. $contents or $block.  Name could also be
specified by optional argument, but that might be an overkill.

For instance,

{include_block file="my-cute-side-block"}
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do
eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut
enim ad minim veniam, quis nostrud exercitation ullamco laboris
nisi ut aliquip ex ea commodo consequat.
{/include_block}

And in file `my-cute-side-block':

<div style="float: right; padding: 1ex;">
$contents
</div>

Does that sound reasonable?  Or is it already possible with other
tag?

Paul