fmtlib uses consteval format string processing, which makes it more
efficient than std::snprintf().
snprintf()s in libuv, mpack, processstarter, and wpigui were left alone.
processstarter uses stdlib only, and wpigui only depends on imgui.
fmt::format_to_n() is analogous to std::format_to_n()
(https://en.cppreference.com/w/cpp/utility/format/format_to_n)
wpi::format_to_n_c_str() is a wrapper which adds the trailing NUL.
This reuses many pieces of the current simulation GUI. The common pieces have
been refactored into the libglass library.
The libglass library is designed to be usable for other standalone data
visualization applications (e.g. viewing data logs).
The name "glass" comes from "glass cockpit", as the application features
several multi-function displays that can be adjusted to display robot
information as needed.