Fixes#2537
This matches Terminal.app. iTerm2 requires cmd+option (our old
behavior). Kitty doesn't seem to support rectangle select or I couldn't
figure out how to make it work. WezTerm matches Terminal.app too.
Outside of terminal emulators, this is also the rectangular select
binding for neovim.
Fixes#2462
This sets up a listener for screen parameter changes. This only triggers
when a screen is added, removed, or a parameter such as its resolution
changes. This doesn't trigger when a window is simply moved from one
screen to another.
On parameter change, we ensure that the window is within the bounds of
the screen. As an exception, if the window was previously already
outside the bounds of the screen, we don't move it back in.
Fixes#2330
The quick terminal now supports fullscreen. The fullscreen mode is
always non-native due to the quick terminal being a titleless, floating
window.
When the quick terminal loses focus and animates out, it will always
exit fullscreen mode.
