Make possible to directly return java Block list in a wiki macro

Currently when for some reason (see for example http://code.xwiki.org/xwiki/bin/view/Macros/NoScriptMacro) you have the Block object in you wiki macro you have too render them to let WikiMacro common parser resolve the blocks.

I would be better to be able to directly return the blocks from a wiki macro. I would also permit to support syntaxes without renderer (like all the wiki syntaxes except xwiki/2.0).

The idea would be to add to the macro context a #return(List<Block> blocks) method.

Something like:

$xcontext.macro.return($blocks)

The result string would still be parsed but only if no explicit return has been done.