Added .gitignore file.
Extracted the SetToken method.
Renamed Ex fields to give them leading upper case.
Re-worked SetToken to move the setting of fields towards the end.
Extracted the SetFunction method.
Extracted the ParseNumber method.
Extracted the SetNumber method.
Removed the 'rank' parameter from SetFunction.
Re-worked the SetToken method.
Removed the set accessor from the Token property.
Un-extracted the SetToken method.
Made the Ex constructor private, and added a static FromToken method in its place.
Moved SetFunction and SetNumber methods.
Moved field-setting code from the constructor to FromToken.
Extracted a more general-purpose constructor.
Converted SetFunction and SetNumber to constructors.
Added .gitignore file.
Moved GetBrushFromExpression and GetPenFromExpression from SolusEngine to SolusParser.
Removed the DefaultInstance field from CleanUpTransformer.
Un-extracted the SolusEngine.CleanUp method. Removed the SolusEngine.CleanUp.cs file.