do cumsum backwards

Calculate a cumulative sum in the inverse order
calculate the differences for trapizoidal integration
plot vertical integrals of observation-model

a verticaly integrated version of fig3diff
create input files for fig3dsum as well
change range and ytics
remove unnecesary file acces
remove extra ylabel comands
use common figure spacing
use common figure spacing in fig7
tweak figure sizes
give figures 1 and 2 descriptive names
change colorbars to improve contrast
remove superfluous plotting command
include the new names for figures 1 and 2
give fig3 a descriptive name
use new name for figure 3
rename the diff and sum of figure 3
fix missing "TSUV", change name in calling function
rename figure 4
move keys to less busy places