I'm still testing this, but I figured, it wouldn't hurt to create a PR for reviewing/discussing.

This implements the execution of ncp apps in tmux if 'tmux: true' i set in their config.
For most purposes, I've tried to make an app to behave exactly the same when run via tmux as it does conventionally.

Features:

• Run ncp apps in tmux (if configured)
• Check if ncp app is already running in tmux before starting it
• Load ('attach' to) execution output when selecting an ncp app in the web interface if it is running in tmux when attempting to launch an app from the web interface while one is running already