Use F12 as "Insert" in macOS terminal

### On Apple keyboards we don't have an Insert key, and this is most annoying when using the command line or CLI tools like Midnight Commander. 

We can fix this by re-assigning the F12 key:
* Remove F12 as key from System Settings->Mission Control
* Enable Use F1, F2, etc. keys as standard function keys in System Settings->Keyboard->Keyboard
* Go to Terminal->Preferences and set the default profile as Pro
* Go to Terminal->Preferences->Profiles->Keyboard and Replace F12 code with `\033[31~`

zenopopovici
12 Aug 2020