Added webcam_resize and some cleanup

I added stdint.h and changed a few unsigned int/chars into uint*_t for
clarification. Also cleaned up the code, so that webcam_streaming
accepts a boolean to turn it on/off.

Lastly, added a webcam_resize, and found out that I need to reset the
buffers after requesting a new frame size, so moved the buffer
requesting into webcam_resize, after the frame resize.