Proj 774 databrowser

Update of the Data Browser, #774 : 

Replaced plot package, updated configuration save/load, fixing several bugs.

Fixes #213, #838, #536, #428, #632, #694, #755, #764, #512

Since it's a substantial change, there are likely remaining issues, but Kunal and I have looked at it and for a few days we're now without known bugs.