Sync from upstream

Add support for ENQ answerback string. You can set the answerback in the Terminal profiles prefs, or via applescript. ^E will cause the terminal to send the answerback string.

Don't allow focus-follows-mouse to make a window key if there is an app-modal dialog open. Issue 4906.

Add an advanced preference to transfrom iTerm2 into a background app. Same as setting LSUIElement in the Info.plist

Change wording of 'thin strokes' to 'sharpen text' and limit it to retina displays since it looks bad on non-retina

Don't draw the Find view's focus ring until it's done animating so it doesn't draw over the tab bar. Modernize some of the OS version checking code.

Otherwise the focus ring is partly drawn above the title bar until the search field
doesn't overlap with the bar

Access app delegate via -[iTermApplication delegate] instead of casting. Also add +[iTermApplication sharedInstance] to reduce type casting.

Access app delegate via -[iTermApplication delegate] instead of casting down from NSApplication APIs

Move logic for removing a profile into ITAddressBookManager and out of the profiles preferences view controller. When removing a profile from Dynamic Profiles, the view controller might not exist. Also, this obviously does not belong in a view controller. Should fix issue 4104.

Nil out PSMTabBarCell's controlView when it gets deallocated to avoid dereferencing it later from a timer. Not quite sure hot to reproduce this bug, unfortunately. It happened when closing lots of tabs at once.

update from upstream

Issue 4032

Fix find view invocation/dismissal animation when height is less than radius.

Testing merge FROM gnachman TO aljex, I hope.

We were over-shooting the initial find view bezier curve drawing, making
the curve->line->curve paths discontinuous on both sides.