See https://github.com/graydon/rust/wiki/Logging-vision
The runtime logging categories are now treated in the same way as
modules in compiled code. Each domain now has a log_lvl that can be
used to restrict the logging from that domain (will be used to allow
logging to be restricted to a single domain).
Features dropped (can be brought back to life if there is interest):
- Logger indentation
- Multiple categories per log statement
- I possibly broke some of the color code -- it confuses me
