[Resource Loader] add dependency system to Resource Reloaders #74

• allow Resource Reloaders to declare dependencies on other Reloaders (i.e. must run after all dependencies have run)
• allow Resource Reloaders to declare dependents of other Reloaders (i.e. must run before dependents have run)

Vanilla has no use for this as it simply registers the Reloaders in the required order, but since mod loading order is undefined there is no consistent order in which mods' Reloaders are registered. There is also currently no way to ensure a Reloader runs before Vanilla's Reloaders, which some mods may require.