[BUG] `portop` kills the terminal cursor

[ncdulo]

Describe the bug
Currently, there are no hotkeys, keybinds, or way to properly exit portop. This is currently handled by sending the SIGINT signal to portop via Ctrl-c into the terminal where the program is running. There is a greater than zero chance that upon exiting portop in that fashion, the terminal cursor glyph will no longer be visible.

To Reproduce

1. sudo portop
2. From main dashboard view -- Ctrl-c
3. Check for visibility of terminal cursor glyph on the prompt which appears in the bottom of the terminal after portop exits.

Note: The current workaround to make the cursor glyph visible again is to simply start another program which plays with the cursor, then exit it. This can be any number of commands from git {diff,log} to man man. It seems that any program which may hide the cursor, or use curses-style interfaces in the terminal may be able to 'reset' our cursor glyph, allowing it to become visible again.

Expected behavior
At the very minimum, portop should capture the SIGINT signal, and act upon it. I believe there is a bashsimplecurses function which is intended to be called as the program exits so that the terminal can be properly restored. For some reason, I did not add this in initially. Now that I see it is actually fairly important (I feel I should have known that from the start), we must add it in.

System
Gentoo Linux 17.1 Desktop profile
Linux 5.4.24 with Gentoo & CK patches
URxvt v9.22
ZSH 5.8 + OhMyZSH
Bash 4.4_p23-r1

[$] [0] <> uname -prm  
5.4.24-ck-x86_64 x86_64 Intel(R) Core(TM) i5-3570K CPU @ 3.40GHz

Additional context
This may require further testing on various distro, terminal, shell setups. If you have tested, or are able to test, I would love a comment with your results -- pass or fail. Please include any relevant information such as shell, terminal, and kernel versions.