Replace logging module with dedicated library

[apple1417]

We have a logging module, but it's very simple and kind of confusing. We should use a dedicated library instead. Ideally:

• Logging goes to file at generally low log level (not debug by default though), with standard logging format.
• Logging goes to console at higher log level, and with less verbosity (just something like [<module>] message).
• unrealsdk.Log in Python takes a module and integrates directly with logging system.
• stdout in Python goes to file as in normal logging, but goes directly to console without special formatting.
• Python functions exist to change log level of file + console separately (/ log format?).

[apple1417]

Done in #114 .

Haven't implemented python stdout catching, that's a separate ticket, but as we're not using any special formatting in console, just sending logging directly should work.