Remove PackKeyFrame

The only thing PackKeyFrame adds to a Frame is a time_tolerance.

Just by this, WOLF now has a complication which is a class PackKeyFrame which is only used to pass information of created keyframe to other processors to join depending on time_tolerance.

By adding time_tolerance to Frame, we can completely eliminate this class and work simply with Frame.

EDIT: Decided to remove time tolerance from frames

TODO:

• Remove BufferPackKeyFrame, substitute by plain BufferFrame
• Remove time_tol from kfCallback() API
• Remove time_tol from setPrior() and similar API
• Move all checkTimeTolerance() methods to ProcessorBase
• Follow on IMU
• Follow on GNSS
• Follow on laser
• Follow on bodydynamics