* Improve redux-devtools-test
Included parts of redux-devtools-2.1.4-tests.tsx
* Use redux-devtools-tests instead of -2.1.4-tests
* No relevant change, simply trigger Travis test build
* oibackoff typing
* Renaming interfaces to drop the I
* Typing with generics and version number
* More cleanup and ensuring things work with strict null checks
* Simplifying oibackoff typing while adding many more generics
* oibackoff: options is optional
* d3-selection
* [Chore]: Completed JSDoc comments
* [Chore]: Removed outdated comments
* [Enhancement]: Added some explicit setter signatures, where using the setter with `null` as a value clears the set attribute, style, property
* [Enhancement]: Added explicit possible `null` return value for `touch(...)` if touch cannot, be found for the fiven identifier
* d3-transition and d3-selection
* **[chore](d3-selection)**: Added JSDoc comments for Selection<...> interface and param priority to style(...)
* **[enhancement](d3-selection)**: Started adding some `| null` for strict null checking. In ValueFn passed into `attr`, `style`, `text`, `html`. Clarifying the ability to clear the respective property when `null` is returned. Also added `| null` to `node()` return type.
* **[chore](d3-transition)**: Added JSDoc comments.
* **[enhancement/fix](d3-transition)**: Updated signatures for `attrTween(...)` and `styleTween(...)` to align them with curent API doc. Added getter, remover and reduced permissible return type for interpolator to `string`. Added getter signature for `tween(...)`
* **[enhancement](d3-transition)**: Added ``| null` in preparation of strict null checking support to ValueFn return types for `attr`, `style`, and `text`. Same with return type for `node()`.
* [BREAKING](d3-transition): Return type of interpolators returned by tween factories in `attr` and `style` has been reduced to `string` as per API doc. (One test was adjusted accordingly)
* d3-transition
* [BREAKING](d3-transition): Fixed signatures for top-level `transition` method. The generics have been updated, as only the datum type in the returned transition needs to be typed. The rest is pre-determined based on a document root selection.
* **[Fix](d3-transition)**: When using an existing transition as an argument, the transition type is not constrained for the argument.
* Adjusted affected tests.
* d3-transition
* [chore](d3-transition): Updated patch version of reference module to 1.0.2
* d3-brush
* **[chore](d3-brush)**: Add JSDoc comments.
* **[Enhancement](d3-brush)**: Added some `| null` to union types/return types in preparation of `strictNullChecks`
* **[Fix](d3-brush)**: Added signatures for removing a brush selection using `null`
* d3-brush and d3-drag
* [chore](d3-brush): Minor addition to JSDoc comment
* [chore](d3-drag): Added JSDoc comments.
* d3-zoom:
* [chore](d3-zoom): Add JSDoc comments.
* d3-force and d3-zoom
* [chore](d3-force): Added JSDoc comments
* [chore](d3-force): Some additions of `| null` or `| undefined` in preparation of strictNullChecks.
* [chore](d3-zoom): Renamed function argument from callback to listener for consistency.
* d3-force
* [chore](d3-force): clarifying edits to JSDoc comments.
* d3-format
* [chore](d3-format): Finalized JSDoc comments
* [Enhancement](d3-format): Use string literals to refine interface FormatSpecifier for properties with specified encoding of choices. (In accordance with D3 API docs)
* d3-timer
* [Fix](d3-timer): Removed brackets from @param statements for optional parameters. Otherwise they did not appear in IDE (VSCode)
* d3-random
* [chore](d3-random): Complete JSDoc comments.
