Version 2 compared to version 1.5 :
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- Now, DDG may handle complex ISA, with multiple register types. Each instruction may write multiple results of distinct types.	
- Add new classes : ARCHITECTURE, REGISTER_TYPES
- Enhancements of precedent classes : adding check methods, adding multiple register types
- Register saturation computation can be done of any register type.
- Bug fix in Register Saturation Computation
- New enhanced XML formats for input/output DDG and architecture description.
- Deprecated DDG file formats: gl.
- Now, DDG is distributed under the LGPL software licence instead of GPL.