Reset flash flag when camera is closed

Closing the camera will also shut off the flash.

This fixes the bug that when you scan a barcode with the flash on and
immediately go back (to the previous instance of CameraActivity), the
flash flag will still be true when the flash is off.

Fix for https://github.com/markusfisch/BinaryEye/issues/101

app/src/main/kotlin/de/markusfisch/android/binaryeye/activity/CameraActivity.kt

@@ -144,6 +144,8 @@ class CameraActivity : AppCompatActivity() {
 
 	private fun closeCamera() {
 		cameraView.close()
+		// closing the camera will also shut off the flash
+		flash = false
 	}
 
 	override fun onRestoreInstanceState(savedState: Bundle) {