Description of the new feature/enhancement

When I work in the terminal (currently mainly CMDer/ConEmu) I like to keep one terminal going with multiple tabs.
When opening a new terminal window, my terminal does not create a new instance of the application but rather opens a new tab in the currently running instance.

Best approach would probably be to make it an option, I.E., not forcing the functionality on people, but rather have it toggle-able for people like me!

Proposed technical implementation details (optional)

Open a terminal while there is a terminal already running opens the running terminal application and creates a new terminal tab, alt. opens the terminal and allows the user to open a new tab manually.

(Love the terminal, it's really neat!)