PUT is too slow

[hgeorgsch]

Too much data are recomputed upon put.

1. We may have to split metadata from traits to avoid having to recompute every charactersheet when timeless data is updated.
2. Birth year may have consequences to later years and may require recomputation.
3. What should be fairly safe is not to recompute the graphs every time an advancement changes. It should suffice to do this when a file is saved.
4. We may need the review #112 to design a good solution,