Roadmap for Code Generation in CLib API

[ischoegl]

This issue aims to track the progress of the C interface portion of #39 with the objective of a complete transition as early as Cantera 3.2. The traditional CLib interface has been declared experimental in 3.1, while a first replacement prototype was discussed in #39 (comment), although it only created header files.

The roadmap involves the following:

• Create working proof-of-concept for a clib-experimental API ... see Experimental clib from doxygen cantera#1835
• Add remaining access functions and unit tests to reach parity with the traditional CLib API:
  • ThermoPhase, Kinetics and Transport
  • zeroD
  • oneD
• Switch dependent APIs to clib-experimental (most functions will have drop-in replacements but include '3' in their name to avoid duplicate symbols):
  • .NET (no change of current approach for code generation)
  • experimental MATLAB (no code generation)
• Rename clib_experimental to clib3 and deprecate (or remove?) the traditional CLib interface. Docstrings should retain the experimental admonition until the API is fully stable (likely in Cantera 3.3).
• Devise SCons/doxygen mechanism so auto-generated CLib docstrings become available in the documentation
• Add new components not available in the traditional CLib, e.g. SolutionArray