A bump in development

Since we last touched it a lot has changed in the dotnet world. This version is MVP updated for Dotnet 8; unfortunately it crashes with OSX, so it's Linux-only for now. (Also, synthetic source locations allow the generated maps to render correctly in the sequence view.)

The dotnet has landed

First public release; only for Linux and the appmaps are still lean and mean and miss a lot of info, but it's a start.
See the README for usage. There's also a short demo at https://asciinema.org/a/402477