Preprocessors like tred or unflatten not available through API
Steps to reproduce
You use Graphviz as a library and want to use unflatten preprocessor.
Expected Behaviour
There should be an API available. That is that we would add the preprocessor
Actual Behaviour
Preprocessor commands are only available through command line. No API available. The preprocessor code is only accessible from a single file command line creating source code file (.c). No headers exist. The code isn't part of any library.
OS Version
All
Graphviz Version
All
Additional info
The code to execute the ingenious unflatten (and other preprocessors) can only be called from the command line. This restricts the use to command line interaction and makes it impossible to use for libraries like the Graphviz WASM.
I suggest to add the preprocessors as functions to the libgraph library - as they represent conversions from one graph to another.