Obfuscate nxsdk information

[drasmuss]

Intel has requested that we obfuscate information related to the nxsdk API (since it is not publicly available). This is an attempt at doing so.

Note that the goal here is not to make the obfuscated information unrecoverable, but simply to obscure it from a surface viewing.

There are three major things I was considering in the obfuscation:

1. Hiding any direct calls to nxsdk objects
2. Renaming any nengo-loihi classes/functions/variables that directly correspond to equivalent nxsdk objects
3. Hiding any constant values (e.g. register sizes) that are based on information inside nxsdk