Rework docker setup

[norpol]

First of all, incredible big thank you for this code. I'm a total C/C++ noob and didn't realize it was that easily possible.

I think there might be some cool ideas possible with this project.

I've managed to get a stream running, for this I've decided to rework Dockerfile and some of the scripts. Although I'm happy to add some of the functionality back. See this pull request as a first draft of a clearer setup. I'm also going to add GitHub action for the docker building maybe.

Anyhow.

• Dockerfile has a builder step that runs make itself
• I've dropped make docker and some of the copying stages
• I've renamed the make commands, this way outdir isn't needed in each command
• I've made outdir overrideable by using ?= instead of = I can do export outdir="dir" since ../ would have been a bit messy inside the Dockerfile
• Simplified the docker entrypoint a bit (I know this is probably less stable)
• Updated the Docker instructions in README

I'm seeing this as a first draft, as I don't know how many changes/which changes you like to get. I'll adjust anything regarding your feedback.

[hisptoot]

Thank you for the improvements. I will check the code and merge your code after I finish the config file generation function.

[norpol]

Thanks for checking it out, please leave some review and let me know if you're happy with the direction. I'm happy to rebase/test everything once you've figured out the #2 solution. I thought maybe adding some WebUI might be cool extension (might be needed anyway if we are doing the oauth-login procedure that the BambuStudio does).