run_tests: pass OPENSSL_ROOT_DIR into perl tests

travis: speed up Travis build

Sign/Verify and tests for all curves

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

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