Fix isEnabledFor() to correctly cache and return level check results
instead of always caching false. Fix _log() to call handle() after
creating the LogRecord. Fix makeRecord() to use Object.keys() and
template literal. Add manager getter and fix setter to actually
assign the value.
Well this started a little messy and I didn't really stick to atomicity. This
was the first script I've written, which was later transferred to the index.
It's the same code just with less structure and some funcitionality missing...
