Ddoc: XREF purge

[aG0aep6G]

XREF and CXREF have been replaced by REF.
STDMOREF has been replaced by MREF.

Be aware that removing the macros from changelog.dd may be controversial. I suggest to discuss this in a central place over at phobos: dlang/phobos#4404

[wilzbach]

Travis failure is unrelated:

Warning: No gpg tool found to verify downloads.
curl: (56) Recv failure: Connection reset by peer
/Users/travis/build.sh: line 45: : No such file or directory

[wilzbach]

ping pong - this just kills unused macros ;-)
@aG0aep6G maybe you can repush, s.t. the Travis build is green?

[aG0aep6G]

@aG0aep6G maybe you can repush, s.t. the Travis build is green?

Done.

[WalterBright]

Auto-merge toggled on