Add more variations of "menu-burger" icon

[XenBG]

The menu-burger icon needs more versions. The standard hamburger menu icon is already obsolete and everybody looking for something fresh and different to use.

Here's an example:

I personally would like to use this one (it's a SVG file you can download and use):

[konchimartin]

Thank you very much @XenBG for your valuable advice, we really appreciate the time you took to write to us about this.

We will take your suggestion into account when assessing what features to introduce next as we continue to improve our product and what we offer.