11_terminal: Set "icon/tab title", not the "window" title
11_terminal: Set "icon/tab title", not the "window" title

Don't set the "window title" at all (and reset it before showing the
new prompt), and set the "icon title" ("tab title") instead: this gives
a much better experience when using tabs in Terminal.app and iTerm2.app,
especially when mixing tabbed and non-tabbed windows.

alexbarton/ax-zsh