make 2.3.1-maint
object_info_reply field is oname, not name
install local mathjax on travis (2.x)

weird CDN things are happening on Travis
Backport PR #6911: don't use text mode in mkstemp

causes double-encoding of newlines, preventing newline arg from having desired effect,
and resulting in CRCRLF line endings on Windows.

closes #6599