Multiline error messages are not printed in their entirety

[trisyoungs]

Describe the bug
The Messenger::error function does not correctly parse and print multiline messages. For example:

Messenger::error("This is part 1.\nAnd this is part 2.");

Only "This is part 1." is printed:

***  ERROR
***  ERROR This is part 1.
***  ERROR

[rprospero]

After a bit of testing, we do mostly print multi-line messages correctly. It is only the last line which is skipped.