Issue title: InternalEdgeDemo memory leak
 Issue body: 
demo should delete btTriangleInfoMap instance assigned to trimeshShape.

 Comments: 
 Comment 0: Closing out-of-date issues.
{'source': 'GithubIssues', 'repo_name_with_owner': 'bulletphysics/bullet3', 'issue_id': 53375840, 'repo_stars': 10147.0}