Remove support for giving the controls variable as it's not really useful when the colormap is defined by two colors.
Remove support for giving the controls variable as it's not really useful when the colormap is defined by two colors.

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