Fix SerializerUnicode to split unquoted newlines

This provides a fix to issue #131. The `split_unquoted_newlines()`
function added to the `utils` module handles the splitting of the string
by performing a simple iteration of the string passed in and splitting
on unquoted CR, LF, or CR+LFs as they are found.

This also required updating the `TestBaseCase.ndiffAssertEqual()`
method to use the new function, because using `str.splitlines()` on
SQL that been formatted with the updated code was producing errors
when trying to do line-by-line comparisons (because the lines were
being split in different places).