adjust AssemblyResolver to ReaderParameters for SubModuleDefs

If you spec an AssemblyResolver in you ReaderParameters when calling read for an ModuleDef/ AssemblyDef the SubModules are still created with an new AssemblyResolver.
I changed that with the changes of this commit.
If that isnt correct I´d like to do that just under some a condition so that you can enable such a behavior/ or impl. something like an SubModuleReaderParametersProvider or that the ReaderParameters have a method create ReaderParameters for SubModules or something like that.