[Kalzium] Titration calculator for 4.6

[Rebetez Etienne]

Hi Luca

I think the titration calculator is not ready for the comming 4.6 release. So 
i suggest moving it to playground. 

The reasons for that are the following:
- I didn't find the time i was hoping for, to help polish the application
- And since you didn't commit anything, i suggest you didn't find the time 
either;)
- The graph (zooming, fit in view, ...) is still very rough.
- Adding a legend for the graph
- Nicer formatting the output of the Theoretical curve (latex?).
- I'am not sure the appproximated curve (tanh) makes much sens for finding the 
equivalence point, since the experimental values are not always symetrical. 
Finding the Equivalent point by searching for the greatest slope would imho 
make more sens. (There can also be more than one equivalence point. ie 
phosphat)

Well, maybe i should have pointed that out more clearly during the review. 
I'am sorry about that.

Etienne