Remove the use of ec_key parameters and return values from ECDSA crypto
prototypes. Don't store key data into an ec_key variable only to fetch
it back into the original type again. Use uint256 and Blob explicitly.
Pass private keys as uint256, and pass public keys as either pointer and
length or Blob in calls to ECDSA{Sign,Verify}() and {en,de}cryptECIES().
Replace GenerateRootDeterministicKey() with separate functions returning
either the public or private key, since no caller needs both at once.
Simplify the use of GenerateDeterministicKey within RippleAddress. Call
a single routine rather than pass the result of one as input to another.
Add openssl unit with RAII classes for bignum, bn_ctx, and ec_point plus
free utility functions.
Rewrite the functions in GenerateDeterministicKey.cpp to use RAII rather
than explicit cleanup code:
* factor out secp256k1_group and secp256k1_order for reuse rather than
computing them each time
* replace getPublicKey() with serialize_ec_point(), which makes, sets,
and destroys an ec_key internally (sparing the caller those details)
and calls i2o_ECPublicKey() directly
* return bignum rather than ec_key from GenerateRootDeterministicKey()
* return ec_point rather than EC_KEY* from GenerateRootPubKey()
Move ECDSA{Private,Public}Key() to a new ECDSAKey unit.
Move ec_key.h into impl/ since it's no longer used outside crypto/.
Remove now-unused member functions from ec_key.
Change tabs to spaces; trim trailing whitespace (including blank lines).
An alternative to the unity build, the classic build compiles each
translation unit individually. This adds more modules to the classic build:
* Remove unity header app.h
* Add missing includes as needed
* Remove obsolete NodeStore backend code
* Add app/, core/, crypto/, json/, net/, overlay/, peerfinder/ to classic build
* Remove CKey dependency on RippleAddress
* Create RAII ec_key wrapper that hides EC_KEY and other OpenSSL details
* Move CKey member logic into free functions
* Delete CKey class
* Rename units that are no longer CKey-related
* Delete code that was unused
