Update Code to Get Rid of 64 bit Compiler Warnings

[jvmahon]

This PR replaces many of the SRC files in the /src with functionally equivalent source from orlp/ed25519. This was done because the functions / variables in the orlp/ed25519 code have more specific type declarations which eliminates the many type conversion (c4244) warnings generated when compiling the original source on 64 bit versions of windows..