Hopefully made cargo use the latest version of rodal (without having to delete cargo.lock or running cargo clean)

simple_logger)

was using nalgebra::DMatrix to implement a graph

1. see vm/vm_options.rs for usage and default values
2. added mu_fastimpl_new_with_opts under vm/api/api_impl/muvm.rs

FIXME: GC settings such as heap size, n_gcthreads, should be properly serialized

gonna port tests to this repo