Added throttling capabilities for high-frequency tf logging

Added tf logging throttling capabilities originally introduced in https://github.com/code-iai/ros-mongodb_log. A transform is only logged when either this transform has not been logged before, or when the new version of this transform is sufficiently different from the one logged before. Additional command line parameters can be used to control how throttling is done:

 * `-k <d>`: Cartesian (vectorial) distance (in meters) threshold between the old and the new transform
 * `-l <d>`: Angular diastance (in deg) threshold between the old and the new transform
 * `-g <d>`: At least log every transform every `d` seconds, even if nothing changed
 * `-a`: Always log, don't throttle
This now changes the default behaviour. In order to get the "old" behaviour one needs to give a new flag `-a`. This should be avoided IMO, as behaviour should be kept the same when additional functionality is it. Do you agree, @fairlight1337 ?