Button to enter command

[justinlaughlin]

It may be nice to have a dedicated button that would then let you type in a command into the terminal, e.g. format. The idea is something similar to : in vim or Ctrl+Shift+P in vscode. : is an unused key at the moment and a potential candidate.

Some keys already require additional user input into the terminal (e.g. F5). Currently this is done using cin >> (ref) but this can lead to GLVis freezing if something erroneous is input (e.g. a string when a number is expected). I have a minimal prompt() function that could maybe be a starting point for input type checking and validation (ref).

For now, the easiest implementation would require inputting the command into the terminal, but eventually it would be nice to be able to directly input the command into the GLVis window.