add wrapper option

[matallo]

it would be useful adding a wrapper or parent option so you can always set the parent where to add the tooltip, instead of fixing it to the body. This is an example of how that code would look like:

var $wrapper = options.wrapper || $('body')

$wrapper.append('<div class = "margintooltip" style = "display:none;"></div>')

Congrats for the snippet, and spurring such inspiration.