Floating hotkey window

This is based on an old patch of yours and fixes https://code.google.com/p/iterm2/issues/detail?id=1570

The weird behauvior you describe is nowhere to be seen, at least not in yosemite. I added some code which sucessfully detected whether the hotkeywindow was over an fullscreen app, but when I couldn't figure out how to move the window up in this case, as my origin.y was seemingly reset everytime. Maybe you know where that's coming from.