Cooling infrastructure

See discussion in email:

• Adopted a common infrastructure for cooling.
• Moved the "constant cooling" to the new infrastructure.
• Created the files for "Creasey cooling". Still need fully working implementation.

@rgb and @dc-arri1 please have a look at this and let me know if you think it makes sense.

@yvesrevaz and @mculpo I hope this helps clarify the implementation of "easy" extensions and will unlock the situation.

Following our chat today, here are a few things to do for @dc-arri1:

• Finish the implementation of "creasey" cooling in the new framework
• rename creasey cooling to something more descriptive.

Status changed to merged

mentioned in commit 153774b2

@matthieu I have just seen the message here, sorry for the late reply and thanks for setting up the infrastructure