1. Use `std::is_standard_layout` and `std::is_trivially_copyable` instead of `std::is_pod` for KV byte-wise serialization, which fixes compile issue for Boost UUIDs
2. Use `std::has_unique_object_representations` instead of `alignof(T) == 1` for epee byte spans and epee hex functions
3. Removed reimplementation of `std::hash` for `boost::uuids::uuid
4. Removed `<<` operator overload for `crypto::secret_key`
5. Removed instances in code where private view key was dumped to the log in plaintext
Partially implements #74.
Securely erases keys from memory after they are no longer needed. Might have a
performance impact, which I haven't measured (perf measurements aren't
generally reliable on laptops).
Thanks to @stoffu for the suggestion to specialize the pod_to_hex/hex_to_pod
functions. Using overloads + SFINAE instead generalizes it so other types can
be marked as scrubbed without adding more boilerplate.
jeffro256