Add tests for input path.

regress/input-modes.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+. ./input-common.inc
+
+start_pane alternate 10 3 'MAIN\033[?1049hALT\033[?1049lZ\n'
+check_capture alternate 'MAINZ'
+
+start_pane osc133 10 4 '\033]133;A\007prompt\n\033]133;C\007output\n'
+check_capture osc133 'prompt
+output'
+check_flags osc133 'P prompt
+O output'
+
+$TMUX kill-server 2>/dev/null
+exit $exit_status