Multiple Splits per Tab

Summary:
This is what I envision for the Konsole Tab / Splits
management. One tab contain a QSPlitter that can contain
multiple TerminalDisplays / Splits.

You can test this behavior by hitting ctrl + shift + 9
and ctrl + shift + 0 to activate the splits, and ctrl +
shift + t to activate a new tab.

Old:

New:

What works:

• Tab Creation
• Split Creation (Even Recursive splitting)
• Terminal Close will close the Split on last split
• Last last split to close will close the tab
• Last tab to close will close konsole
• Detaching
• Tab Renaming
• Closing splits after detach
• Closing windows after detach
• Detach / Reattach works!

This patch series has the commits of Thomas Surrel, Maciej Niedbdalski and Myself.

Reviewers: Konsole, hindenburg

Reviewed By: Konsole, hindenburg

Subscribers: luc4, hallas, anthonyfieroni, gennad, ngraham, thsurrel, maciejn, mglb, hindenburg, konsole-devel

Tags: Konsole

Differential Revision: https://phabricator.kde.org/D17643