Test signature verify for different parameters

This will make at least signature verification work.

R 1323565.1.023-2018 defines in the `parameters' for
`AlgorithmIdentifier' field `digestParamSet' is optional.

Interoperability with third party software.

Look at `test_params.c` for example.

Replace orders of groups with orders of cyclic subgroups

According to OpenSSL documentation EC_GROUP's member named order contains the cardinality of cyclic subgroup. Some paramsets contain cardinalities of elliptic curves' groups.

benchmark: Extend sign/verify benchmark.

- Cycle through all supported parameters.
- Also do verification tests.
- Increase precision of timer (allow test to work faster).

benchmark is done separately.

Split and integrate tests

Move test code from gost_keyexpimp.c into separate test_keyexpimp.c and
link into test target.

Also, make tests work without requiring config.

Add LICENSE file to satisfy the lawyer in you

Cmake improvements

The directory can be overriden by setting the CMake variable OPENSSL_ENGINES_DIR

CMakeLists.txt uses `add_test` to execute `test/run_tests` which does the same thing as the `prove` line did.

GOST 28147-89 test suite from
https://github.com/openssl/openssl/blob/26906f2d93ad4bc092b8b5783d1b35f8c9f0c6d8/engines/ccgost/gost2814789t.c
WIP

Test to validate curve parameters