Eslint does not pass

[sebastiansandqvist]

If we can get the current code to pass eslint checks, then it can be made a rule that eslint must pass prior to merging a PR.

Most of the current difficulties come from the the jsx-a11y eslint plugin, which does not allow, for example, onClick handlers on static elements like a <span>. In some cases, the css makes it so that a specific element to be used, so these linting rules cannot be easily fixed.

I avoided adding several // eslint-disable-line comments in those cases, since in general those linting suggestions are good and should be addressed in the future.