(feat SensorModelling) add pixel_order field

refers to #620
Adds a "pixel_order" field and enum to allow mirrored versions of the pixel layouts.  This is the result of the discussions with the participants in the sensor modelling workgroup meetings.

Signed-off-by: RIFJo <jochmann@rt.rif-ev.de>

Author: RIFJo

osi_sensorview.proto

@@ -313,8 +313,10 @@ message CameraSensorView
 
     // Raw image data.
     //
-    // The raw image data in the memory layout and order specified by the
-    // camera sensor input configuration.
+    // The raw image data in the memory layout specified by the camera sensor
+    // input configuration. Default pixel order is left-to-right, top-to-bottom
+    ///(think of scan lines in a TV), but modifications can be 
+    // requested/indicated in CameraSensorViewConfiguration.pixel_order.
     //
     optional bytes image_data = 2;
 }

osi_sensorviewconfiguration.proto

@@ -729,6 +729,52 @@ message CameraSensorViewConfiguration
     //
     repeated WavelengthData wavelength_data = 11;
 
+    // Indicates if and how the the pixel data is ordered
+    //
+    // By default, the pixel data is is left-to-right, top-to-bottom. 
+    // 
+    // \note for rotations of the pixel data, use the camera coordinate system
+    //
+    optional PixelOrder pixel_order = 12;
+
+    // Pixel layout 
+    //
+    // Pixel layout documents the order of pixels in the \c image_data
+    // in CameraSensorView. 
+    //
+    // \note this enum does not contain an entry to do mirroring upside down
+    // and left-to-right at the same time, because this is equivalent to a 180°
+    // rotation, which should be indicated in the sensor coordinate system 
+    //
+    enum PixelOrder
+    {
+        // Pixel order is unknown (must not be used).
+        //
+        PIXEL_ORDER_UNKNOWN = 0;
+
+        // Unspecified but unknown pixel order.
+        // Consider proposing an additional format if using
+        // \c #PIXEL_ORDER_OTHER.
+        //
+        PIXEL_ORDER_OTHER = 1;
+        
+        // Pixel data is not mirrored (Default).
+        // Pixels are ordered left-to-right, top-to-bottom
+        //
+        PIXEL_ORDER_DEFAULT = 2;
+
+        // Pixel data is mirrored along the vertical axis.
+        // The image is mirrored left-to-right.
+        //
+        PIXEL_ORDER_MIRRORED_LEFT_RIGHT = 3;
+
+        // Pixel data is mirrored along the horizontal axis.
+        // The image is mirrored top-to-bottom.
+        //      
+        PIXEL_ORDER_MIRRORED_UP_DOWN = 4;
+    }
+
+
     // Channel format.
     //
     enum ChannelFormat