Reverted call to loglog to System.err so logback users can also use the debug command.

I've removed reference to loglog.error as this was stopping logback users from seeing debug messages as they did not have the log4j dependancy and loglog is also not in the slf4j adapters.
From log4j source, the call to loglog.error just prints to System.err anyway
http://grepcode.com/file/repo1.maven.org/maven2/log4j/log4j/1.2.17/org/apache/log4j/helpers/LogLog.java?av=f#124

Additionally I've Also Changed INVALID_TOKEN and QUEUE_OVERFLOW to use LINE_SEP instead of unix carriage returns.

And Added dbg message to display queue size when socket writer was interrrupted
I think we should leave this hard-coded to `\n` for now- if you want to raise another issue with this fix then feel free, but I think it's out of the scope of the LogLog fix.