Fix "Connect anyay?" text in SSH authenticity prompt

Don't try to open the password manager sheet when it's already open. Leaves dangling references to the released window controller. Issue 5983

You now do iterm2.run(f) to run a function `f` within the iterm2 context.

Add session.read_keystroke()

Refactor various classes into their own files

Don't go into an infinite loop when trying to convert positions with w idth of 0. Hopefully fixes issue 6005

Beta 8 does not have crashes in OffsetOfWrappedLine. Increase testing fraction to 10% since I haven't seen any crashes yet in the nightly build

Don't search more than 500,000 cells in a very long line to avoid hangs. This is tricky to split up into multiple searches since lines can change.

Refactor timer stuff into a single file.

Defer decreasing the frame rate until the next frame is drawn to try to avoid issues like 5928.

- Enable it for nightly build users
- 1% of lookups are checked for correctness, leaving a crashlog on failure
- Clear the DWC cache when dropping a line. I beleive this was the cause of the assertions in beta 6 and 7.
- Make the check for nightly build faster

Update tab bar sanity check to log when dragging ends (it was called too soon) and to log more info. Issue 5055

Don't log all sendAction: calls because it crashes a lot when formatting the string. Maybe some kind of object has a bad -description method.

Disable number-of-wrapped-lines cache. There's a very common crash in OffsetOfWrappedLine starting in beta 6. This is the likely culprit. Issue 5980

Disable ligatures-across-different-backgrounds when muting is in use (cursor boost and dimming use this). A background color is needed to compute the dimmed value.

Fix a bug where numberOfEquivalentRows was always 0 when minimum contrast is 0, which caused text to have the wrong foreground color.

Issue 5961