Add mode parameter for command

[fpohtmeh]

Add mode parameter for command.

• Normal is the default value.
• {"n", "v"} for commands which work in both modes
• Commands are hidden if they aren't supported in the current mode. Or the user gets a notification if he uses a command in the wrong mode. 2nd is better IMO because the user still sees the full list of commands

Reason:

• Some commands make a mess if a visual selection is empty. For example: sort

[DanWlker]

I thought about this for a while. This is implementable, but I don't think its necessary.

When you're in visual mode and press :, it auto shows visual selection, then you can type in your command. If you don't want a visual selection then you should not select in the first place, and the command should error.

The current behavior now is in line with the default neovim behavior. Therefore I am probably not going to add something that has a different default behavior from what neovim does. It would also have the benefit of being somewhat consistent and easy to debug for the end user.

However, I will keep this open as i think i need some time to think about it as well.

Thank you for the suggestion.