added first ideas for extension

extend.md

+collect new scripts for video recording, processing & streaming:
+
+compile a ready to use raspberry image
+
+
+cameras:
+
+    usb webcam
+        https://www.kurokesu.com/main/2016/01/16/manual-usb-camera-settings-in-linux/ 
+    raspi camera module 
+
+
+toolkit:
+
+    ffmpeg
+    opencv
+    python
+    numpy 
+
+
+control options:
+
+    button ? 
+
+
+    bluetooth:
+        make android bluedot app for control (start/stop/new/stream /
+        https://hacks.mozilla.org/2017/02/headless-raspberry-pi-configuration-over-bluetooth/ 
+
+
+    wifi:
+        accespoint function for control [raspberry wlan ap traincam] 
+
+
+    other:
+        storage: usb
+            usbmount still does not work, have to compile, see https://www.raspberrypi.org/forums/viewtopic.php?t=192291#p1280234 
+