Atoms color fixes

[Luthaf]

Fix #319 and some related code and layout cleanup.

@MaximeScope could you give this a look and check that everything works as intended?

[ceriottm]

Ghost environments are fixed, had some issue with the color scale remaining even after switching to element coloring, but might have been down to non-updated widgets. when switching environments on and off and then on, it doesn't switch to environment highlighting until an atom is clicked on, IDK if that is intended or a bug

[Luthaf]

had some issue with the color scale remaining even after switching to element coloring, but might have been down to non-updated widgets

If you manage to reproduce let me know I'll try to fix it.

[Luthaf]

when switching environments on and off and then on, it doesn't switch to environment highlighting until an atom is clicked on, IDK if that is intended or a bug

Should be fixed now, we just go back to the previously selected center

[ceriottm]

when switching environments on and off and then on, it doesn't switch to environment highlighting until an atom is clicked on, IDK if that is intended or a bug

Should be fixed now, we just go back to the previously selected center

Works.

[ceriottm]

fixed legend layout. @Luthaf only thing I can't seem to manage to fix is the position of the modal, that at least on chrome seem to ignore completely what goes into positionsettingsrectangle

[ceriottm]

Fixed also the alignment I think

[Luthaf]

I cleaned up the commits, this is good to go for me!