Nicer pyglet import error message if version not high enough
Nicer pyglet import error message if version not high enough

The version of pyglet that we need is not released yet. So one needs to
do "pip install http://pyglet.googlecode.com/archive/tip.zip".

Also added a note; I found that the pyglet process events function
does not really process paint events, but this might need further
investigation.

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