travis-ci: switch to xenial

test_tls: simple TLS connection testing

Generate cert for every parameter, set it up on s_server, connect
s_client, and transfer 1M of data to both directions.

Migrate test framework to Test2

At least Fedora 30 will have no Test::More anymore. Test::More is
deprecated, as well as Test::Stream and Test2 is a recommended
replacement.

Luckily, gost-engine's use of Test::More is limited to functions which
are compatible with implementations in Test2, so only module import and
test plan announcement need to change.

Also, on Fedora 29 perl 5.28 is very picky on undefined variables.

tests: Load just built engine from the output directory

Define ENGINE_DIR for all binary tests. Instead of auto-loading engine
using `example.conf' load it directly from the OUTPUT_DIRECTORY for
curves tests.

cmake: benchmark/sign - link with rt for clock_gettime when needed

Test if clock_gettime() requires linking with -lrt and link sign
benchmark with rt if needed. clock_gettime() requires -lrt only for
glibc versions before 2.17.

travis: Enable ASan build

Fix leaks in tests

In preparation for memory leak detector fix them in the tests.

Implement EVP_PKEY_{,public_}check

Very simple redirect to EC_KEY_check_key() which is doing all basic
checks (see crypto/ec/ec_key.c:ec_key_simple_check_key()).

 test_params: remove calls to internall API and add more tests

- Manually verify cert using EVP_Verify API. (In addition to
X509_verify).
- Add test using EVP_DigestVerifyInit API for raw vectors.

run_tests: pass OPENSSL_ROOT_DIR into perl tests

travis: speed up Travis build

Sign/Verify and tests for all curves

Use external API to generate key with parameters instead of calling
fill_GOST_EC_params(). Use OPENSSL_CONF trick like in test_sign to avoid
calling bind_gost(). Reverting 1716316d ("Export bind_gost to allow
local engine init") as not needed anymore.

Currently, not all curves are tested, but only these that are fully
implemented, to test all curves run `test_sign` with any argument.

R 1323565.1.023-2018 forbids encoding hash oid into TC26 (2012)
parameters in AlgorithmIdentifier, so this is removed.

New "paramset" names for 256-bit TC26 parameters: TCA, TCB, TCC, TCD,
for 512-bit parameter: C.

Using these new OIDs for gost2012_256:
  NID_id_tc26_gost_3410_2012_256_paramSetA = TCA
  NID_id_tc26_gost_3410_2012_256_paramSetB = TCB
  NID_id_tc26_gost_3410_2012_256_paramSetC = TCC
  NID_id_tc26_gost_3410_2012_256_paramSetD = TCD
for gost2012_512:
  NID_id_tc26_gost_3410_2012_512_paramSetC = C

Resolves #84.

If OPENSSL_ROOT_DIR is specified pass it to the perl tests, and set its
value as LD_LIBRARY_PATH, if unset. This allows to run tests for custom
openssl build without manually setting proper env.

Do shallow clone of openssl, make parallel on all available cpus (2).

Enable test for 2001 curves since they are allowed and add TC26
aliases for 256-bit curves.

Test signature verify for different parameters