Move the CMake file into the directory
Add a base class for all elements
Add enumeration types used in BulletML
Add an expression parser and evaluator
Handle whitespace in expressions
Check for operator arguments
Store the result of the parsing
Add unit testing for expressions
Add an empty runner module
Improve the element base class
Rename the MotionType enumeration
Implement some of the simpler elements
Add a way to distinguish elements
Add an exception for missing elements
Implement the simpler compound elements
Add TODO items for remaining elements
Add an empty file for the top-level element