Modern Build System and Readme

[redagito]

This branch adds a modern conan/cmake based build system and separate builds for all the demo projects. I tested it on windows 10 and linux and it builds and runs on both systems. The changes to the project structure are pretty major but the original source code was left mostly untouched except where I had to fix warnings/errors.

I would love to get some feedback. My fork is actually much further ahead but the changes are much more intrusive and probably have no chance of getting merged.

[xem]

thanks, but on Windows "conan install" fails with the following message:

ERROR: There are invalid packages: fmtlog/2.2.1: Invalid: Current cppstd (14) is lower than the required C++ standard (17).

(there's no C++ redistributable >= 14.0 on Windows as far as I can tell)

[redagito]

Thanks for the feedback, I just now read your message and will try to find time to look into the issue.