__FUNCTION__ and debug.

I'd like to introduce a new debug api:

trace(section, level)(const char *format, ...);

This will over time replace debug() as the primary debugging output
tool.

trace will have the following semantics:
It will prepend the __FUNCTION__ macro to the format string:
ie "Can't lock foo" in somefunc() will output as
"somefunc: Can't lock foo".

It won't enforce, but also won't support, embedded \n characters.

Any objections or minor tweaks?

Rob