New Converter API

Up to and including libSBML-5 it has been possible to convert SBML models between the various SBML Levels and Versions. The introduction of Level 3 packages makes the combinations of possible conversion expand exponentially and we have for some time realised that the existing api was not sufficient. Thoughts on this are outlined here.

Further discussion lead us to the conclusion that it would be beneficial to treat 'converters' as modules in a similar fashion to the L3 package modules. Code could then choose to register a converter with properties that would indicate the nature of the conversion and allow a user to customize the functionality. Sarah and Frank outlined this in a presentation at COMBINE 2011.