Improvements for Vertical page

[guidocioni]

• Add SkewT plot with temperature and dewpoint as function of pressure
• Add callback that uses the time instant where the user clicks on the first vertical plot to select when to do the SkewT
• Add height values on the right side, together with the pressure values that are on the left side (use a mean of the geopotential height maybe)
• Instead of masking the cloud cover array with NaNs try to modify how the contour is filled to avoid drawing cloud covers for values less than 10. See here https://stackoverflow.com/questions/64200865/colorbar-doesnt-respect-limit-values
• Improve the logic to handle any missing variable and not plotting it
• Adjust every parameter for models that have less time extension (like ICON-D2).