Save panes set up as workspace

[Jomme5]

It would be nice if:

• panes setup and working directories can be saved in seperate sessions or workspaces. So if you are on one project, you can easely switch to another.

[Chouille]

Replace the '+' button terminals list by a panel with different terminals as nodes and workspaces as subnodes with there settings.
Will be awesome ! :)