handle multiple columns, add population concentration

Signed-off-by: Daniel Halperin <dhalperi@cs.washington.edu>
add FSC, hide legend if only one type, and remove useless ids

Signed-off-by: Daniel Halperin <dhalperi@cs.washington.edu>
using divs for better, more understandable layout

Signed-off-by: Daniel Halperin <dhalperi@cs.washington.edu>
add temperature, salinity, fluorescence

Signed-off-by: Daniel Halperin <dhalperi@cs.washington.edu>