Add keybindings for CTRL, ALT, SHIFT + UP, DOWN, RIGHT, LEFT, HOME, END, BACKSPACE, DELETE & more (#3996)

* Added tests for `LightRenderer`

* Added common SHIFT, ALT and ALT+SHIFT key sequences

* Added common CTRL key sequences

* Added common CTRL+ALT, CTRL+SHIFT, CTRL+ALT+SHIFT key sequences

* Added proper xterm META modifier handling

according to defc6dd568/input.c (L357-L375)

* Fix `ctrl-backspace` and `ctrl-alt-backspace`

* Fix broken tcell tests on windows by swallowing Resize events

* Added tests for  FullscreenRenderer

* Removed own fork of tcell and updated tcell to 2.9.0

tcell 2.9.0 is needed for `Ctrl-Alt-*` and `Ctrl-Alt-Shift-*` shortcuts in Windows

* Replace conditional checks with switch statements to improve readability

* Replace long conditionals with constant slices to improve readability

* Bind `ctrl-bspace` (`ctrl-h`) to `backward-delete-char` by default

Since we now distinguish between Backspace and Ctrl-Backspace, Ctrl-Backspace should trigger the same action as Backspace by default. In that way nothing changes for the user but you can bind other actions to Ctrl-Backspace when desired.

src/terminal.go

@@ -782,6 +782,7 @@ func defaultKeymap() map[tui.Event][]*action {
 	add(tui.CtrlF, actForwardChar)
 	add(tui.CtrlH, actBackwardDeleteChar)
 	add(tui.Backspace, actBackwardDeleteChar)
+	add(tui.CtrlBackspace, actBackwardDeleteChar)
 	add(tui.Tab, actToggleDown)
 	add(tui.ShiftTab, actToggleUp)
 	add(tui.CtrlJ, actDown)