Finally, a graph visualisation

See merge request behaviors-ai/the_dashboard!6

The configuration of each gadget is now managed with MobX. It means that we get rid of the mechanisms of FlexLayout and that we can configure items that are not displayed in FlexLayout.
Also, The configuration and readme mode are now displayed as a modal overlay over the whole web page. This is still WIP, but much better on some aspects than before.

Limitation : for now, if two tabs are instantiated with the same gadget inside, the configuration would be common to both. It clearly should be fixed.

The data of the interaction trace object were stored in the global MobX store with the key "interactionTrace". To prepare for the further work, I changed it to match the name of this object as it is known to FlexLayout.

Dgoepp/fixes#1

See merge request behaviors-ai/the_dashboard!5

Moving visualisation title in the menu according to Ninon's zeplin + centering

See merge request behaviors-ai/the_dashboard!4

Merge branch 'dgoepp/config-modules' of https://gitlab.liris.cnrs.fr/behaviors-ai/the_dashboard into dgoepp/config-modules

This reverts commit 208e9f52.

There was a bug in the case where the same field was taken frop several topics. The data of each topic would be appended to a single line.