scene: fix syntax error on Python 2.x
scene: fix syntax error on Python 2.x

Removed simplify kwarg from ChainTransform. We need to figure out
how/when to do simplification and caching anyway.

hronoses/vispy,hronoses/vispy,Eric89GXL/vispy,kkuunnddaannkk/vispy,QuLogic/vispy,julienr/vispy,michaelaye/vispy,sh4wn/vispy,dchilds7/Deysha-Star-Formation,hronoses/vispy,sbtlaarzc/vispy,RebeccaWPerry/vispy,dchilds7/Deysha-Star-Formation,julienr/vispy,julienr/vispy,sbtlaarzc/vispy,drufat/vispy,srinathv/vispy,kkuunnddaannkk/vispy,sbtlaarzc/vispy,QuLogic/vispy,jdreaver/vispy,srinathv/vispy,Eric89GXL/vispy,bollu/vispy,inclement/vispy,ghisvail/vispy,dchilds7/Deysha-Star-Formation,ghisvail/vispy,RebeccaWPerry/vispy,sh4wn/vispy,inclement/vispy,drufat/vispy,jay3sh/vispy,jay3sh/vispy,bollu/vispy,jdreaver/vispy,michaelaye/vispy,srinathv/vispy,QuLogic/vispy,michaelaye/vispy,ghisvail/vispy,RebeccaWPerry/vispy,sh4wn/vispy,Eric89GXL/vispy,bollu/vispy,jdreaver/vispy,kkuunnddaannkk/vispy,inclement/vispy,drufat/vispy,jay3sh/vispy