RippleAddress:  Cull unused humanAddressType()
CKeyECIES:  Cull unused (and undeclared) checkECIES()
CKey:  Remove unreferenced or commented-out code
CKey:  Remove unused fSet member

fSet is only evaluated when assigned to another instance of fSet.
Remove CKey dependency on RippleAddress
Rename CKey.cpp to CKey.test.cpp

This file doesn't define anything declared in CKey.h, but it does define
CKey_test.
[FOLD] Fix CKey.test.cpp include
ec_key:  Add very thin EC_KEY wrapper class