'''Richard's page'''

* It is very tedious at present to use the same model on a different data set.
Either - get the "data source" drop down at top of fit page to work to change data
Or - change "send to" then "fitting" to instead have "current fit page" or "new fit page" - '''Now #747'''


* Could possibly save results of every fit so that "wind back" to previous results 
is possible - but could get very messy for simultaneous fits etc. - '''Now #745'''

'''Need look at constraints & polydispersity again.''' 
* If possible, would be useful to add a fittable parameter that can be used within
constraints.  e.g. I want (Rcore+Tshell)/Rcore = C 
this requires constraint for Tshell = Rcore(C-1)  where C can be fitted.
This would save having to write variant models, BUT constraints may need to be 
called inside polydispersity integrations for say Rcore , which may not be possible here. [FISH does this] - '''Now #746'''