dep: added All the Maths‽ (AM).
premake: added -Wno-missing-braces for Clang.
premake: moved Beard dep (and its deps) to onsang-client-deps.
Net/CmdStreamer: corrected Log::acquire() calls.¹

1: Hord commit 99a460f52b0ce6869d19b49b6603a8bb1b7f4c4d makes Log::acquire()
default to Log::general and puts Log::Pre::current.
Error: added get_error_name() and some error codes.
Log: added report_error() functions for Hord and Onsang.
Added class ConfigNode.
Client: added class Unit and stubbed basic flow.