Syntax highlighting broken with multiline inputs

[impact27]

To reproduce:
jupyter qtconsole
Then paste a multiline statment, e.g.:

"""
s
"""
a = 1

This results in:

Only the first line is highlighted

[ccordoba12]

This probably happens because we're using Pygments to highlight single lines. And I think that's the only way to use Pygments interactively (i.e. not for entire documents).