Fix a problem where setFrame:display: on a window would annoy constraints, which caused the window to get resized to the wrong height. It was caused by the "bugFixView", which did not play nicely with constraints. Constraints exist on the window now when a titlebar accessory is present. To repro the bug, simply run tmux -CC attach, and observe that there's a bit of gray at the bottom of the window frame.
Don't allow one iTerm2 to attach twice to the same session.
Minor cleanup of previous commit
Merge branch 'master' of https://github.com/gnachman/iTerm2