Pt. Grey flycapture2 backend: intermittent failure on Windows

[motmot]

This happens sometimes with release 0.6.0 on Windows:

Traceback (most recent call last):
  File "threading.pyc", line 486, in __bootstrap_inner
  File "threading.pyc", line 446, in run
  File "fview.py", line 225, in grab_func
  File "cam_iface_ctypes.pyc", line 425, in grab_next_frame_into_alloced_buf_blocking
  File "cam_iface_ctypes.pyc", line 407, in grab_next_frame_into_buf_blocking
  File "cam_iface_ctypes.pyc", line 292, in _check_error
CamIFaceError: C:\Documents and Settings\astraw\My Documents\src\motmot\libcamiface\src\cam_iface_pgr_flycap.cpp (1006): 
PGR FlyCapture2 err 34: (No new buffer.)