Disabling old split view, adding default shortcuts...

[mjobin-mdsol]

so, code quality is NOT really good... I just hack this together to make it work more like I wanted it to behave.

• old split options are not readilly available, but there sure remain codes to delete.
• options in the menu no longer appears and I did not care too much
• I use keyboard shortcuts, I used something similar to what iTerm2 on OSX has a default Meta-d to split horizontally and Meta-Ctrl-d to split vertically
• Meta-w close that has focused.
• we still have that bug where the window remains open with no more terminal after closing the last one
• simplify code where I could, reusing existing signals instead of creating new ones...

[vincepii]

Manually merged including some fixes.