Fix handling of arrow keys with alt and/or shift modifier

Fix #2254

- Properly handle extra chars in the buffer. Patch suggested by @mckelly2833.
- Support alt-arrow sequences in \e[1;3A format
- Support shift-alt-arrow sequences in \e[1;10A format

src/tui/tui.go

@@ -98,6 +98,11 @@ const (
 	AltLeft
 	AltRight
 
+	AltSUp
+	AltSDown
+	AltSLeft
+	AltSRight
+
 	Alt0
 )