- Implemented a DampingMoment simulation listener example

- Implemented a DampingMoment simulation listener example
- Added ability for simulation listeners to reserve their own data types. To support this:
  -- All data types can now be found from just the OpenRocketDocument (reduces some code duplication also).
  -- Custom expressions rebuilt after loading from file in case they use a listeners reserved type
- Fixed (possibly unrelated) issue where datatypes would be deleted and re-made each step if a customexpression used a range or index subexpression

git-svn-id: https://openrocket.svn.sourceforge.net/svnroot/openrocket/trunk@1021 180e2498-e6e9-4542-8430-84ac67f01cd8