bindings from appearing in the generated documentation. This can
be enabled with `--no-dotnet`, `--no-z3py`, and `--no-java`
respectively.
This fine-grained control is being added for the CMake build system
which will need this control.
(`--output-dir`) to control where output files are emitted.
This is implemented by making `z3api.dox` a template file
(renamed `z3api.cfg.in`) and populating the template at build
time with the required settings.