Port to libbase58/libblkmaker

[luke-jr]

Better to use the dependencies directly rather than bundle a copy of them

[jesterhodl]

You mean add a submodule of https://github.com/luke-jr/libbase58 and use that instead of thirdparty_base58* ?

I could do that if there are no differences, or any potential differences from datum_gateway would need to go upstream to your fork of libbase58

[luke-jr]

No need for it to be a submodule, these libraries can be installed and used via pkg-config the same as the rest. See #14

The bigger project is rewriting the code to use libblkmaker to create the blocks and parse the GBT results.