• feat #404 added GridStackOptions.fitToContent and GridStackWidget.fitToContent to make gridItems size themselves to their content (no scroll bar), calling GridStack.resizeToContent(el) whenever the grid or item is resized.
• also added new 'resizecontent' event, and resizeToContentCB and resizeToContentParent vars.
• fix #2406 inf loop when autoPosition after loading into 1 column, then 2.