Add contact icons from image files

[MrGreensWorkshop]

Is your feature request related to a problem? Please describe.

Although you want to add some icons, it's not always available in fontawesome. There is no way to add it.

Describe the solution you'd like

• only black colored and transparent png or svg image files could be used.
• works with adding paremeter to _data/const/contact.yml

  your_new_contact:
  icon: "https://www.clker.com/cliparts/8/T/Y/I/3/E/black-spade-th.png"
  url: "https://www.example.com"

  for local images

  your_new_contact:
  icon: "/assets/img/default/new_icon.svg"
  url: "https://www.example.com"

• icon path availibility for these 3
  • "/" (local)
  • "http://"
  • "https://"

	default	on hover
default color scheme
dark color scheme

Describe alternatives you've considered

upgrading fontawesome adds some new icons but you can't always find icon that you want.

Additional context

none

[MrGreensWorkshop]

done with #43