[minor] Error management
Added a new type of event, that triggers on value change
[minor] Correct event thread naming
Initial support for multiple lowlevel middleware

ROS + NAOqi imported from pyrobots v1.

While here, add aliases to set the logging level to debug, info or warning
Added method to cancel all actions except the current one
Pass the GenericRobot instance to the event callbacks

This means that event callbacks are now *required* to take a robot instance as first
parameter. This makes @action good candidates for event callbacks.
[minor] Shortcut for frame transformation when no transformation is actually required
Fix thread naming issue for event threads