* refactor: cleanup va_start/va_end
- Missing va_end statements;
- Incorrect va_copy ordering in BFR_VSNPRINTF;
- Sanitize snprintf results or ensure buffer is initially \0'd.
* refactor: introduce vasprintf
Replace dynamic format string allocation (i.e., incrementing a buffer by
a fixed amount until vsnprintf returns success) with vasprintf.
Polyfill'ing for builds that do not include the GNU extension.
* chore: run codespell on source/header files
Fixes most reported typos discovered by codespell (while trying to be
unopinionated about American vs. British English).
* chore: run codespell on build/readme files
* add emulated HIM device to connect MTS to the Internet.
A HIM is a Host Interface Machine which provides an interfave between
the Michigan Terminal System (MTS) and the Internet.
* Cosmetic changes only.
* Move some declarations to keep old compilers happy.