refactoring for encrypted-pem→secret-key → created helper & constants;

add read/write functions for structured data with PEM;

fixed security provider registration;

add data armor functions with signature.

encryption, mac using GOST 28147-89, GOST 3412-2015;

digest, hmac using GOST3411-94/2012 256 and 512 bits;

signature using GOST3410-2012 256 and 512 bit key length;

key generation: secret keys, public/private keys, password based keys;

compression + encryption + mac / decryption + check mac + decompression

save/load keys (secret, private, public) to PEM format.