fixup function to strip numpy types
ROS compatibility: do not automatically emulate ROS with incompatible Bag files
ROS compatibility: give warning when writing non-bag file
always use our own quaternion functions (never from ROS)
 reduce overloading of ROS name
move ROS-specific test to own module
do not import ROS until needed. no need for ROS for YAML.
move ROS tests to single module
Merge branch 'cleaner-ROS-separation'