/*!
 * remove all children of parent element
 * gist.github.com/englishextra/da26bf39bc90fd29435e8ae0b409ddc3
 * @param {Object} e parent HTML Element
 * removeChildren(e)
 */
var removeChildren=function(e){if(e&&e.firstChild)for(;e.firstChild;)e.removeChild(e.firstChild)};