threaded network chat refactor

The code has been refactored and it compiles. Hopefully it won't explode, but that if it does, that just means we have actual meaningful work to do.

TODO

• Finalize coding style,
  • see STYLE.md
• Get everyone's editors set up for clangd/clang-format and git
• Make sure everyone's compiler toolchains work
• Decide who gets what responsibilities
• Distribute appropriate code to people with those responsibilities
• Have everyone upload their respective code to their sections of the gitlab

Code

Everything is in src/. A mostly untouched copy of scott's original code is also in old/. A reformatted version of that code is also in modified-example.cc but it can be ignored.

Build

cd src/
make