Release D 2.087.0

[Mike Franklin]

On Monday, 15 July 2019 at 12:40:50 UTC, Vladimir Panteleev wrote:

> - core.internal.hash contains the implementation of hashing 
> routines used for associative arrays.
> - core.internal.arrayop contains the implementation of array 
> vector operations. This one doesn't seem to be too far from 
> your work in question.

... and are the exception, not the rule.  I believe they should 
be moved to `rt`.