Feedback form: Ported Feedback form to v4.0

Includes following fixes to vapour.js to enable this port:
* Added params function from v3.1 to getURLParts (makes it easier to access query string parameters)
* Improved compatibility with multiple wb.pluginame values in the same class attribute (previously failed in such scenarios)

Includes other tweaks to vapour.js:
* Changed leading spaces to tabs
* Boosted performance of various functions