Disable cache in reader code

[mauserrifle]

The README states the following:

# Caching
Some classes like Participant do heavy caching. So changing any value after calling sorting methods will be pointless. There are no cache invalidate methods (yet). Most likely they will never be needed as there's no use case you actually would want to change values after reading out all data.

When writing a reader. NEVER call methods like getVehicle() on Participant (which uses cached methods). Re-use your own created objects (like $vehicle) within the reading to prevent any early invalid cache. Do this for all type of objects.

It would be great if this would just be prevented to disable the cache during reading and enable only after successful reading. This way no bugs can ever exist in the future due (too) early cached method calls in the reader.