Make background single-use commands use system() instead of opening a short lived window because it goes nuts when this is done in a fullscreen desktop. Issue 6033

Restore currentTerminal, accidentally removed in 78cba9be. Issue 5959

searching all sessions with current selections for the one whose selection
was created most recently. This way even if the selection is emoved, you
can still paste it. Brought up in email, subject line "Keep selected text
in buffer until I select another text (like Mac terminal does)".

Refactor the man page viewer into a more general single-purpose window. Add a smart selection action to run a command in a single-purpose window. Issue 5862.

Make it possible to open the tmux dashboard if there are no windows opened and the tmux gateway is buried. Issue 5835

When you drag a tab from the tabbar into a split pane, that causes removeTab: to be called. It tries to create a restorable session to undo closure, but because no sessions actually get closed in this operation we create an empty shell of a restorable session. When it's restored, you get a zombie tab with no view. This commit ignores such operations and declines to push a restorable session on the stack. Issue 5785.

Validate hostname of ssh URLs and reject anything besides letters, numbers, dash, and colon. Colon is allowed for IPV6. Square brackets in IPV6 get stripped by the system.

Change "Open in current space" for hotkey windows to move the hotkey window to the current space if it's already open on another space when the hotkey is pressed. Issue 5622.

This fixes a bug where sometimes orphans would open before windowDidDecodeRestorableState ran and you'd get both a "session restored" and an orphan when they should have been merged. To reproduce the bug prior to this commit:

1. Open a window
2. Cmd-I, change colors
3. Force quit
4. Restart
Observe that you get two windows, one orphan and one session restored.

Offer to repair saved arrangements when a profile exists with the same name as the profile a session was created with.

Make it possible to save a hotkey window in a saved arrangement. Fix a bug where restored hotkey windows get an extra tab. I'm a little nervous about what this change might break, but I tested it and it plays nice with session restoration, default arrangements, and explicit saved arranagement restoration whether there's already a hotkey window or not. Issue 4924.

Merge in code from hotkeyWindowsInPanels branch. Support multiple hotkey windows. Update the shortcut input view. Add support for floating panel terminal windows.

When arranging windows horizontally, wait for all windows to exit fullscreen first. This requires queuing up toggle fullscreen operations, so the iTermFullScreenWindowManager got revamped to handle this.

Refactor code that decides if the hotkey window should be hidden when a window resigns key. Add a feature to try to detect when spotlight is opened to not auto-close the hotkey window when that happens. The new feature is behind a default-off flag because I'm sure it'll do something unexpected. It should be turned on by default in the 3.1 beta.

Move keyWindowIndexMemo out of iTermController and into HotkeyWindowController where it belongs, and rename it to a more sensible name.