Handle %pprint correctly

[sagetrac-tmonteil]

From the IPython REPL launched from Sage (by running sage --ipython in a terminal),
we can switch off pretty printing as follows:

In [1]: [10**13]*5
Out[1]:
[10000000000000,
 10000000000000,
 10000000000000,
 10000000000000,
 10000000000000]

In [2]: %pprint
Pretty printing has been turned OFF

In [3]: [10**13]*5
Out[3]: [10000000000000, 10000000000000, 10000000000000, 10000000000000, 10000000000000]}}}

However, from the Sage REPL itself, or in a Sage Jupyter notebook, this does not work:

sage: [10^13]*5
[10000000000000,
 10000000000000,
 10000000000000,
 10000000000000,
 10000000000000]
sage: %pprint
Pretty printing has been turned OFF
sage: [10^13]*5
[10000000000000,
 10000000000000,
 10000000000000,
 10000000000000,
 10000000000000]

Does this come from a broken interaction with Sage's own
pretty printing features (which focus more on latexing)?

This was reported on Ask Sage twice:

• Ask Sage question #37477: long list goes vertical
• Ask Sage question #42509: unexpected interface behaviour

CC: @vbraun @tscrim @fchapoton @slel @seblabbe

Component: user interface

Keywords: pprint

Issue created by migration from https://trac.sagemath.org/ticket/22968

[slel]

Changed keywords from none to pprint