remove redundant/dead code
Comment casting errors caused by variable length API integers.
Declare virtual on implementations of pure virtual methods.
Comments and warning suppression for secp256k1.
Compress message text.
Add explicit obelisk codec descructor and virtual method override keywords.
Tweak virtual method stuff (clang fix for missing vtable).
Add missing virtual destructor definition.
Cosmetics.
Restore request_stream/response_stream symmetry.