Load files with arbitrary names

Currently, load(0 works by detecting the file type depending on the file name suffix. In case of yaml libraries, especially, it must end up with `.lib.yml` which is not always desired (you might just want to have the standard `yaml` suffix).

I suggest this limitation could be lifted by explicitly defining the type we want to load at load time. This could be achieved by separate functions such as `loadYaml()` or `loadStarlark()`.

Another alternative would be to add a parameter to `load()` but this would be a backwards incompatible change.