Refactor forms to implement react-final-forms

[sepulzera]

React sucks at forms. There are plenty of libs for forms that suck too.

Anyway, not using any libs sucks even more. Thus I will go with react-final-form. I won't use formik because it has poor performance, as changing a field will re-render the whole form.

React-final-forms seems to be right choice, but its docu sucks.

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By solving this issue, I hope to rule out some other nasty bugs and performance issues, like #59, submit button disabling behaviour and onSubmitSuccess-Callbacks. I also expect quite some performance gains, especially for the recipe form ingredients groupbox. I don't expect the code to become any cleaner or easier to re-use; react sucks too much in this regard.