Merge remote-tracking branch 'origin/61-image-bug' fixes #61

* origin/61-image-bug:
  Fixed image path
Merge remote-tracking branch 'origin/colormap_rebased'

* origin/colormap_rebased:
  brought back solid color shader and cleaned up detection of scalar type
  Removed shader that hard-coded the color
  Added API to set / get scalar format
  Comments and fixes
  Add color map capability to vgl proper.
  add color map
  restore rendering demonstrations/tests
optimize geojson import
Merge remote-tracking branch 'origin/optimize_data_path' into next

* origin/optimize_data_path:
  optimize geojson import