WebUI: Update third-party WebUI/JS dependencies

[jens-maus]

The following external WebUI javascript dependencies (which are located in /www/webui/js/extern/ on a CCU) should be evaluated to be updated with newer versions available:

• builder.js, dragdrop.js, effects.js, scriptaculous.js, slider.js (http://script.aculo.us/downloads)
• excanvas.js (https://github.com/arv/ExplorerCanvas)
• jqplot.*.js, jquery.jqplot.min.js (https://github.com/jqPlot/jqPlot/)
• jquery-ui.min.js (http://jqueryui.com)
• jquery.blockUI.js (https://github.com/malsup/blockui/)
• jquery.dd.min.js (https://github.com/marghoobsuleman/ms-Dropdown)
• jquery.form.js (https://github.com/jquery-form/form)
• jquery.js (https://jquery.com)
• jquery.powertip.js (https://github.com/stevenbenner/jquery-powertip)
• jquery.ui.timepicker.js (https://github.com/fgelinas/timepicker)
• jqueryURLPlugin.js (https://github.com/allmarkedup/purl)
• json2min.js (https://github.com/douglascrockford/JSON-js, https://www.cdnpkg.com/easyXDM)
• knockout.js (https://github.com/knockout/knockout)
• less.js (https://github.com/less/less.js)
• nfs_datepicker.js (https://www.nsftools.com/tips/nsftoolsDatepicker.js)
• prototype.js (https://github.com/prototypejs/prototype/)
• sliderControl.js (https://www.softcomplex.com/products/tigra_slider_control/)
• spectrum.js (https://github.com/bgrins/spectrum)
• template.js (https://code.google.com/archive/p/trimpath/downloads)
• wz_jsgraphics.js (http://www.walterzorn.de/en/jsgraphics/jsgraphics_e.htm#download)

More WebUI dependencies that might enjoy some updates could be added here.