Avoid private typedef functions

[timsneath]

Avoid private typedef functions

[timsneath]

I've reduced the number of private typedefs (deleting typedefs.dart and moving the C-style API functions to inline function declaration). This is a good thing -- it substantially improves code completion and documentation since the analyzer can now see the method parameters.

I don't plan to do the same with COM and WinRT interfaces, however, because it pushes dart format to insanity.

See for example:

  int CreateInstance(Pointer<COMObject> pUnkOuter, Pointer<GUID> riid,
          Pointer<IntPtr> ppvObject) =>
      Pointer<
                  NativeFunction<
                      Int32 Function(
                          Pointer obj,
                          Pointer<COMObject> pUnkOuter,
                          Pointer<GUID> riid,
                          Pointer<IntPtr> ppvObject)>>.fromAddress(
              ptr.ref.vtable.elementAt(3).value)
          .asFunction<
              int Function(
                  Pointer obj,
                  Pointer<COMObject> pUnkOuter,
                  Pointer<GUID> riid,
                  Pointer<IntPtr> ppvObject)>()(ptr.ref.lpVtbl, pUnkOuter, riid, ppvObject);

and

    final hr = Pointer<
                    NativeFunction<
                        Int32 Function(
                            Pointer obj, Pointer<Uint32> value)>>.fromAddress(
                ptr.ref.vtable.elementAt(6).value)
            .asFunction<int Function(Pointer obj, Pointer<Uint32> value)>()(
        ptr.ref.lpVtbl, retValuePtr);

There's no equivalent return here for the end-user in return for the loss of readability: the parameters are already well-exposed.