Enable other rules for eslint

[bartekleon]

As we were talking with Nico in #1731, there are some rules, which could be turned on, as well as tslint rules which are introduced one by one to eslint.
We could make some list which should be enabled.

[simondel]

Hi @kmdrGroch! Right now you have 13 open issues. Could you perhaps merge related issues (such as types and eslint rules) and/or remove obsolete issues?

filter: https://github.com/stryker-mutator/stryker/issues/created_by/kmdrGroch

[brodybits]

I would personally not favor combining too many issues together. Just my (US) $0.02 worth as an outsider.

[simondel]

I agree that simply grouping everything together may not be the best plan. However, tracking multiple issues regarding eslint rules for example is also not ideal for maintainers. I'd prefer a single issue in such a case with and up to date list of things that have to be fixed.

[bartekleon]

put everything in #1834 :) @brodybits, @simondel