Fully fixed and merged the first POSIX cleanup item

Well, would you look at that! That took significantly less time than the Windows fix. It is partly because it was a smaller fix and only part whole POSIX fix, while the Windows one was the whole thing and also the foundation had already been laid out from the Windows work and I just integrated the POSIX path into that, but it is also very much because Microsoft is a horrible, terrible company that can’t make good software. I mean, look at GitHub, they have been going downhill ever since they got acquired by Microsoft.
Now that I got that out of my system, here’s what was fixed:

• If the program cannot enable raw mode at startup, it safely fails instead of continuing and corrupting the terminal state

• If the cleanup gets interrupted, it retries cleanup so it doesn’t leave the terminal state corrupted after one failed attempt

Onto the next POSIX fix: handling SIGQUIT and SIGHUP.