Added bynamic brake blending info (7.3.4), and CurveForceControlled/CurveForce_Inc_Past/CurveForce_Dec_Past sound parameter informations to the manual.
git-svn-id: http://svn.uktrainsim.com/svn/openrails/trunk@3420 a9f3cfff-6c41-7446-b0ca-052bd761e6eb