Generated bindings

[MrCyjaneK]

All of the code in here (and in monero.dart) should be autogenerated (it is not).

This involves parsing the upstream c++ header, generating corresponding C header, c++ wrapper, dart ffi wrapper, dart "actual" wrapper, and possilby even dart wrapper that respects the C++ classes.. In either case it is not happening for at least some time now because of the amount of work required to make this.