Two reasons: to match GOST R test vector size, just make it bigger.

openssl-1.1.0 made ctx opaque and does not allow it on stack anymore.

Previously, we had shim layer in our openssl branch
Could be squashed with 01d26132

Co-authored-by: Mikhail Gordeev <obirvalger@altlinux.org>

Also, document why CTR IV size is now set to 16, so user is noted to set
IV appropriately to full extent (including counter). Basically, it's for
openssh (and alike) to make it copy IV from privilege separated process.

Encrypt with small chunks to verify that internal state is handled
correctly between calls.

These tests are with generated test vectors from canonical TC26
implementation with truncated IVs.

Previous implementation was not OFB at all, and fail tests.

Note: This implementation is for fixed width 128-bit IV which makes
shift regiser redundant.

Full test of OFB to match GOST R 34.13-2015 test vectors is impossible,
due to test IVs are having size (256-bits) over the maximum openssl can
allow (128-bits).

I generated new test vectors from canonical implementation
from `PR_GOSTR_bch_v9.zip` (revision of 2016-10-28) by truncating test
IVs in half.

Make sure stream modes can encrypt any block size.

Previously CTR did not continue unfinished block on the next cipher
iteration.

test_grasshopper: test modes to match GOST vectors
Only ECB and CTR modes are tested. OBF, CBC, CFB modes is not testable
under openssl.

Offset commit 7f572e958b13041056f377a62d3219633cfb1e8a
Old openssl still needs EVP_MD_FLAG_PKEY_METHOD_SIGNATURE flag to be
set.

Fix a mem leak

Ensure the grasshopper ciphers are destroyed on engine destroy.

modernize ci

(*) convert 'openssl ciphers | grep ...' into Test:More syntax
(*) enable some tests on travis-ci (04 is yet broken)

modernize ci

initial travis-ci support