Switch to ASCII arrows (#1418)
Switch to ASCII arrows (#1418)

Fixes #1226.

I will miss the Unicode arrows.
nteract/nteract,jdfreder/nteract,captainsafia/nteract,rgbkrk/nteract,captainsafia/nteract,nteract/nteract,nteract/composition,jdetle/nteract,temogen/nteract,jdfreder/nteract,rgbkrk/nteract,jdfreder/nteract,captainsafia/nteract,rgbkrk/nteract,nteract/nteract,jdfreder/nteract,rgbkrk/nteract,nteract/composition,captainsafia/nteract,rgbkrk/nteract,temogen/nteract,temogen/nteract,jdetle/nteract,nteract/composition,nteract/nteract,nteract/nteract,jdetle/nteract,jdetle/nteract