Added pages for 6 datasets.

Added images from 6 new datasets

Added visualizations from 3 datasets.

- Coal brikett 3D added

- Added voxel sizes
- Removed background from histograms
- Set ratio similar for all images
- removed axis numbers from plots
- text fixed

Mussel, Coal and Foam.
Added images and a folder 'pages/' with their a corresponding .html page for each dataset