Add rollingsum filter for frame analysis based on column mean deviation

- Implements GStreamer element that analyzes pixel columns
- Drops frames when column mean deviates from rolling baseline
- Configurable window size, column index, stride, and threshold
- Includes design documentation and build script
- Tested successfully with IDS uEye camera source

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION "2.8.0")
+cmake_minimum_required(VERSION "3.5.0")
 
 project(gst-plugins-vision)