Extend the board attribute 'minimizeReflow'

This attribute now accepts three values 'none', 'svg', and 'all'. The first will not remove anything from the DOM during a board update. 'svg' will remove only the SVG root node and will leave the text elements with display set to 'html'. 'all' removes the whole board before an update and readds it after the update is finished.
Update JessieCode