Merge branch 'refs/heads/t/rm_oaep'

The open-coded OAEP padding removed in this series is no longer needed
since all supported libgcrypt versions support OAEP padding.

The series also contains a few follow up cleanups for gcrypt.c.

Cooking for three months.

* refs/heads/t/rm_oaep:
  gcrypt: Simplify init_random_seed_or_die().
  gcrypt: Rename E_OEAP to E_RSA_DECODE.
  gcrypt: Remove open-coded OAEP padding.

diff --cc NEWS.md
index 771e12df19c0a72efe530b5d880ab375404d44e6,d9326db76cfa80b50a8a268fef1b29f966cdeb09..fb6665293bbd45acc8a1cf892f4773e7c0d86156
--- 1/NEWS.md
--- 2/NEWS.md
+++ b/NEWS.md
@@@ -1,20 -1,6 +1,22 @@@
  NEWS
  ====
  
 +------------------------------------
 +0.6.0 (to be announced) "fuzzy flux"
 +------------------------------------
 +- Support for Mac OS X has been removed.
 +- On Linux systems, glibc-2.17 or newer is required to build the
 +  source tree.
 +- Support for RSA public keys in ASN format (as generated by openssl
 +  genrsa) has been removed. These keys have been deprecated since
 +  2011, so users should have long switched to keys generated with
 +  ssh-keygen(1).
++- If libgcrypt is used as the crypto library, we now require version
++  1.5.0 (released in 2011) or later.
 +
 +Downloads:
 +[tarball](./releases/paraslash-git.tar.bz2),
 +
  -------------------------------------
  0.5.7 (2016-12-31) "semantic density"
  -------------------------------------

diff --cc error.h
Simple merge

diff --cc gcrypt.c
Simple merge