Sundials upgrade

[ergoregion]

This PR updates the code to work with sundials 7.5.0.

• The install_cvode script has been updated to use sundials 7.5.0
• There are changes to the atchem2 file to use the new version of cvode.
• There is a change to OutputFunctions because the means of displaying the data about the run is changed
• The skeleton of the makefile now requires a new field CVODEOBJDIR the place where thee fortran object files are stored
• the readme and docker install scripts have been updated to try to tell people about the new makefile setting

This can be made neater with further code changes, I left the main right hand side function FCVFUN unchanged, and invoked it from the new cvode method,
Consolidating these methods would be a wise move.
The class of UserData could be neatened to store named variables, instead of old-style arrays of ints and reals

[ergoregion]

replaced with #545