Low level bindings for C API, adapted from https://github.com/catboost/catboost/tree/master/catboost/rust-package.
Major differences are:
* Splitting out from the main repo due to the catboost repo being very big
* Change strategy from rebuilding the shared library from source (which makes it hard to publish as a crate) to downloading it from the github official releases
* Fixes to make it work for M1 macs (to download the right libcatboost binary)
* Most changes are in build.rs, no differences in the APIs
* We keep a copy of the model_interface c_bindings from https://github.com/catboost/catboost/tree/v1.0.6/catboost/libs/model_interface in this repo to simplify things
apt-get install -y build-essential pkg-config libssl-dev libclang-dev clang cmake
cargo build