Fix the for loop
Merge branch 'master' of github.com:vispy/vispy

* 'master' of github.com:vispy/vispy:
  Fixed --vispy-gl-debug problem by moving glGetActiveAttrib workaround to glapi.py
  fixed stupid
  Added command line flag for printing GL calls as they are made
  Fixed mouse behavior in oscilloscope
  Added command-line flag for switching backend
  Make scrolling more consistent (delta should be float)