Bug fixes Part 2

- If the internal v4l2 grabber is switched off, it will now be de-initialized (Issue: #542)
- Extended error detection in MJPEG decompress method
- Default instance capture activation if it is missing in the configuration (https://hyperion-project.org/goto/post?id=13656#post-13656)
- Fixed some small (think)mistakes (https://hyperion-project.org/threads/hdmi-grabber.3302/page-2#post-14887)

src/hyperion-v4l2/hyperion-v4l2.cpp

@@ -26,14 +26,6 @@
 
 using namespace commandline;
 
-// save the image as screenshot
-void saveScreenshot(QString filename, const Image<ColorRgb> & image)
-{
-	// store as PNG
-	QImage pngImage((const uint8_t *) image.memptr(), image.width(), image.height(), 3*image.width(), QImage::Format_RGB888);
-	pngImage.save(filename);
-}
-
 int main(int argc, char** argv)
 {
 	Logger *log = Logger::getInstance("V4L2GRABBER");