Add display_png example
Add display_png example

ibm-et/IRkernel,mikecroucher/IRkernel,ChinaQuants/IRkernel,elaOnMars/IRkernel,Phobia0ptik/IRkernel,rgbkrk/IRkernel,JanSchulz/IRkernel,gdtm86/IRkernel,chendaniely/IRkernel,ibm-et/IRkernel