This commit rewrites the log() function so that it will append a
newline at the end of the message if none is present. It doesn't make
sense to print a log message without a newline since the next log
message (which will write a prefix) expects to be starting at the
beginning of a line.

Although it isn't strictly necessary, this commit also removes any
newlines at the ends of messages. If I missed any, including the
newline at the end of the message will continue to work as it did
before.

Previously, some calls were missing the newline at the end even though
including it was necessary for subsequent messages to appear
correctly.

This code also cleans up some redundant prefixes. The log() method
will prepend the prefix and the different processes should set their
prefix as soon as they start.

Multiline messages are still supported (although the prefix for the
additional lines was changed to match the length of the prefix used
for the first line).