Fix #2529: explicit protection package #3651

[Kagamin via Digitalmars-d-announce]

On Wednesday, 20 August 2014 at 09:40:37 UTC, ketmar via 
Digitalmars-d-announce wrote:
> imagine mybiglib, mybiglib.internal, mybiglib.other, and each 
> of them
> not single module, but package itself. so we have module
> mybiglib.other.thingy which wants to use functions from
> module mybiglib.internal.wisdom, which is part of 
> mybiglib.internal
> package.

Do we need a hierarchy of internals, is the problem this big? Why 
mybiglib.wisdom is not good?