graph: rework edge renderer based on rectangle renderer

Closes #759

See merge request !523

[graph] restore proportional labels and make edges transparent

See merge request !522

[notifications] add possibility to notify user from the backend

See merge request !520

[graph] fix updateGraph function so that labels are rendered properly

See merge request !521

Resolve "Inject commit hash in the version popup"

See merge request !517

This was visible in the screenshot, where forceAtlas is not started
initially and there were no labels, even though the setting was correct.

Resolve "Problem with related terms"

See merge request !518

It was reduced by 1 because the currently selected term was also
counted. Now the algorithm changed, so we don't need to subtract 1
anymore.

Dev support emitting warnings

See merge request !519

This way errors are red, warnings are yellow.

[Node terms] Show related docs for children terms as well

Closes #680

See merge request !516

Related to
#747

Needs corresponding backend API changes.

Resolve "Share link copy to clipboard"

See merge request !512

modify css on legend + graph settings parameters

Closes #743

See merge request !513

[graphql] simplify and_logic for get contexts for ngrams

See merge request !515

fix: disable button

See merge request !514

Resolve "Display graph parameters in legend"

Closes #706

See merge request !510