[MRG] Update markdowncv to include icons, customizable colors with a new template

[ccbaumler]

This fixes missing icons in the webaddress bar in the header by including the missing link (ha!) for fontawesome and academicons in the html file (located in markdowncv's resources directory). I have also updated the existing academicons fonts and css to version 1.9.4 and included the missing ttf file (also version 1.9.4).

This also adds yaml header options for various text colors:

1. headcolor changes the header (h2) color for the sections of the CV
2. addresscolor changes the webaddress bar containing the various icons and different user addresses
3. codecolor changes the code block color which is typically the when argument (i.e. the date in the final CV)
4. backcolor changes the background color of the document (for that dark mode!)
5. textcolor changes the text color of the document (so you can see the text in dark mode...)
6. namecolor changes the name for a more dynamic header

When applied to the marie curie template the yaml header looks like:

---
title: CV
name: Marie
namecolor: "#777"
surname: Curie
position: "Professor"
address: "School of Physics & Chemistry, École Normale Supérieure"
phone: +1 22 3333 4444
pronouns: she/her
www: mariecurie.com
email: "Marie.Curie@ens.fr"
twitter: mariecurie
github: mariecurie
linkedin: mariecurie
date: "`r format(Sys.time(), '%B %Y')`"
aboutme: "Marie is a Polish and naturalized-French physicist and chemist who conducts pioneering research on radioactivity."
headcolor: "#E1BE6A"
addresscolor: "#107895"
codecolor: "#777"
backcolor: "#000"
textcolor: "#FFF"
output:
  vitae::markdowncv:
    theme: ccbaumler
---