Add bilibili icon/link to footer social links

[SenlinOS]

I have made the SVG icon:
https://github.com/SenlinOS/databox/blob/master/bilibili.svg

[xianmin]

Thanks for the icon. Now bilibili icon is supported.

[SenlinOS]

I just wrote a HTML icon bar, manually replaced the code, it can be amended later @_@

---

Thank you for updating so quickly.
I looked at the effect and felt the icon was small.
So I enlarged the icons. (The size is still 128 x 128.)
https://github.com/SenlinOS/databox/blob/master/bilibili.svg

E-mail is best not to use pop-up windows.

[xianmin]

OK! I updated.
By the way, it's easy to Increase icon font size use custom.css.

Maybe you could open another issue talk about E-mail suggestion.