Update API documentation.
Add removeOverlay() and ability to force render.

Add the removeOverlay() method.
Add the partiallyUninterprete() method.
Add the $force second argument of the render() method.

So now, we are able to do such thing:

    $xyl->addOverlay('Overlay1.xyl');
    $xyl->render();

    $xyl->removeOverlay('Overlay1.xyl');
    $xyl->addOverlay('Overlay2.xyl');
    $xyl->render();

\o/
[auto] Merge from Xyl

    • #81fd335 — Update API documentation. (Ivan Enderlin, 2013-08-15)
    • #366b422 — Add removeOverlay() and ability to force render. (Ivan Enderlin, 2013-08-15)

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Merge remote branch 'library-xyl/master'