Trivial: ByteArray thoughts

[lauckhart]

Some quick ideas r.e. ByteArray.

• Right now we monkeypatch Uint8Array, might be frowned upon by some library users
• Could we make ByteArray a subclass of Uint8Array instead of an alias, and put utility functions there?
• We could also add custom toString and toJSON methods so diagnostics like in #138 would show as hex rather than comma-separated decimal
• I could also add the base64 utilities using the codec I made for the security stuff

[Apollon77]

@mfucci introduced it that way. I think the idea was that on other platforms it might nbe something else then UInt8Array, thats why "just" the alias.

@mfucci Any opinion on this?