Does D support middle endianness?

[Valentino Giudice]

The only reference I found was this thread from 11 years ago: 
https://forum.dlang.org/post/mailman.1953.1380926372.1719.digitalmars-d@puremagic.com

I'd argue that if there aren't many middle endian architecture, 
it'd be worth not supporting them, in exchange for only having to 
deal with two byte orders (rather than all possible 
permutations), so the specification should mandate that either 
LittleEndian or BigEndian be set to true.