Adding an issue form

[wawuwo]

Hi!

@ra3xdh @zergud what do you guys think about adding an issue form to the project? It allows to define a general structure for an issue with mandatory and optional fields, etc.

I've created such a form for bug reports, you can play around with it in my fork https://github.com/wawuwo/qucs_s. Try to file up a new issue and you'll see :) This is how an issue made from that form look likes