Update readme to reflect version 3.5.3

Update CHANGELOG to include 3.5.2, fix version numbers in README.

Updated to use 3.5.1 in examples rather than 3.5

[ci skip]

Change release date.

[ci skip]

Merge pull request simbody#133 from j-rivero/simbody-3.4

Update debian metadata for simbody 3.4

Merge pull request simbody#124 from tkuchida/PLUSImpact

Overloaded geometric step length calculations to handle 3D vectors.

Update version number to 3.3.1.

This is the version that was used by Jose Rivero at OSRF to build a d…

…ebian to release with Gazebo.

This is the source for Simbody release 3.1. This is the version of Si…

…mbody

that is used by OpenSim 3.1.

This is the source for Simbody patch release 3.0.1.