Add Makefile and rasterized formats

[rradczewski]

As agreed in #3, this PR replaces website-logo.png with a vectorized version (now svg/codebar-logo-banner.svg) and adds a Makefile that will create rasterized versions of the logos at different resolutions.

I also added a brief explanation to the README.

[KimberleyCook]

Hi Raimo. Thanks for your work on this!

Could we adjust the readme to explain why we need this command and in what situation you would use it? So that someone maybe not as tech savy understands the benefit.

Also, I'm wary that there's a lot of complexity here for our average contributor and I'm wondering if we could simplify it a little. Personally I think pngs are preferable for solid colour logos like this and if we remove the jpeg processing we can simplify the makefile and remove the dependency on imagemagick. What do you think?

Cheers,
Kimberley

[rradczewski]

I understand your points @KimberleyCook 🤔 I wonder how frequently this repo is used by whom - maybe it's a good idea to hide this information in a CONTRIBUTE document if most people only come to download the images (e.g. I imagine event organizers or companies that host codebar events use this repo for their promotional stuff).

How about we address people who come to download the images in the README and move all information regarding changing the content of the repo into CONTRIBUTE?

[rradczewski]

Re Makefile and jpeg: I figured the Makefile might be interesting to people learning about ecosystems that use make and all, which is why it's a bit more sophisticated but with a lot of comments explaining how it works.

I'll happily remove the JPEG 👍