Add --display-orientation

Deprecate the option --rotation and introduce a new option
--display-orientation with the 8 possible orientations (0, 90, 180, 270,
flip0, flip90, flip180 and flip270).

New shortcuts MOD+Shift+(arrow) dynamically change the display
(horizontal or vertical) flip.

Fixes #1380 <https://github.com/Genymobile/scrcpy/issues/1380>
Fixes #3819 <https://github.com/Genymobile/scrcpy/issues/3819>
PR #4441 <https://github.com/Genymobile/scrcpy/pull/4441>

app/scrcpy.1

@@ -141,6 +141,14 @@ The available display ids can be listed by \fB\-\-list\-displays\fR.
 
 Default is 0.
 
+.TP
+.BI "\-\-display\-orientation " value
+Set the initial display orientation.
+
+Possible values are 0, 90, 180, 270, flip0, flip90, flip180 and flip270. The number represents the clockwise rotation in degrees; the "flip" keyword applies a horizontal flip before the rotation.
+
+Default is 0.
+
 .TP
 .B \-e, \-\-select\-tcpip
 Use TCP/IP device (if there is exactly one, like adb -e).
@@ -369,10 +377,6 @@ Supported names are currently "direct3d", "opengl", "opengles2", "opengles", "me
 .B \-\-require\-audio
 By default, scrcpy mirrors only the video if audio capture fails on the device. This option makes scrcpy fail if audio is enabled but does not work.
 
-.TP
-.BI "\-\-rotation " value
-Set the initial display rotation. Possibles values are 0, 1, 2 and 3. Each increment adds a 90 degrees rotation counterclockwise.
-
 .TP
 .BI "\-s, \-\-serial " number
 The device serial number. Mandatory only if several devices are connected to adb.
@@ -534,6 +538,14 @@ Rotate display left
 .B MOD+Right
 Rotate display right
 
+.TP
+.B MOD+Shift+Left, MOD+Shift+Right
+Flip display horizontally
+
+.TP
+.B MOD+Shift+Up, MOD+Shift+Down
+Flip display vertically
+
 .TP
 .B MOD+g
 Resize window to 1:1 (pixel\-perfect)