unnecessary blank line before errors

[aavogt]

When making a mistake, there is an extra empty line:

perhaps the markup can be adjusted somehow? Compare with how the python backend looks (no Out[])

[gibiansky]

Hmm, looks like this isn't just a markup issue. I think IHaskell is sending a py_out as well as display_data message, and the py_out empty message is the blank line. Will investigate further.

[gibiansky]

Should be fixed in 4fe42de

Also, error messages now have '\n' replaced with HTML line breaks.

[aavogt]

One case that is missed:

Maybe this will go away by addressing #14