Improved acceleration smoothing, see issue 19 for details

This change is likely to have implications on our agents' behavior if
they have a low acceleration smooth rate.  Make sure you understand the
implications before updating to this version.

https://github.com/ricardojmendez/UnitySteer/issues/19
New SteerForMinimumSpeed post-processing behavior
DegreeEditor no longer needs a trailing tab
Release notes for 2.6
Merge branch 'release/2.6'