Improve bundling of custom JavaScript and CSS assets

[amotl]

Hi there,

this patch removes assets which have been inlined into this repository before and replaces them by a bundling system based on yarn and webpack. It will resolve #241.

With kind regards,
Andreas.

[nomicode]

will let @msbt review this one :)

[msbt]

I've tried that build and it works fine! All I had to do was

sudo apt update
curl -sL https://deb.nodesource.com/setup_14.x | sudo bash -
sudo apt-get install -y nodejs
sudo npm install --global yarn

beforehand, then it ran through as expected, nice work @amotl!

[amotl]

I've tried that build and it works fine! All I had to do was [install Node.js and yarn].

Thank you. I've added respective instructions through 8d9af3a.

[amotl]

I also removed Fontawesome completely through 4b37ec0.

[msbt]

looking good!