threaded network chat refactor

The code has been refactored and it compiles. Hopefully it won't explode, but we were going to be doing a bunch of bug fixes anyway.

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