Changed "log" and "logger" to "mlog" throughout the library

This is to avoid conflicts with the logarithm function
on some systems in some situations.

The Sawyer test cases still tend to use "log" as their local
variables, which is fine since they're not including anything
that defines the logarithm function.
Avoid initializing the library when creating plumbing

Since "mlog" is now initialized with streams when it is statically
constructed, we need to avoid initializing the library when creating
mlog's FdSink.  Otherwise, we get runtime errors from the C++ library
because it hasn't had time to initialize itself yet.