Fix Tortuosity filter and make sure it passes the test

A few things here:
 - Fix test comparison value
 - Fix normalizations to make sure we don't divide by 0 and get NaNs
 - Remove completly useless dynamic_cast
 - Misc fixes of codes badly rewritten when switching from the logic to
a filter
 - Add epsilon parameter for future testing of the filter.

Change-Id: I0af3c60c7ccb4f00601a3da82bd7b6cb9ff93945