v4

*File weight halved.
*More fluid animations.
*The interval function has been removed, now the resize function adjusts
the div's position when the window is resized.
*From now on, the maximum width shall be declared in the CSS.
*gapL and gapR can now be overridden through the function without
modifying the plugin.
*You can now choose what type of TAG, when clicked, will close the
sidebar.
*Functions to be called are halved thanks to the implementation of the
attribute data-sbplugin.