- Improvements to sensor detection
- Fixed "plist[] defined but not used" warning
- Now uses OV511_NUMSBUF to determine number of sbufs
- Moved buffer alloc/dealloc code to ov511_alloc() and ov511_dealloc(), and
  their helper functions, ov511_do_dealloc() and ov511_buf_callback().
- Added new parameter, buf_timeout, which is amount of time in seconds before
  unused buffers are freed. Default is 5.
- buffers are now deallocated if disconnect occurs while open
- Various code cleanups and optimizations
- ov511.h: Set SCRATCH_BUF_SIZE to 512; fixes crash with YUV422 sensor mode
- ov511.h: Removed useless STREAM_BUF_SIZE define
- ov511.h: Added buf_state enum
- ov511.h: Added buf_state, buf_lock, and buf_timer to usb_ov511 struct
- ov511.txt: Updated