refactor object spreading logic

per [this review comment](https://github.com/bengreenier/overlayed/pull/32#discussion_r222395313) there is a better way to do object spreading that is being used to extend an existing object with additional properties.

For instance:

```
const existing = { a: 'ayy' }
const modified = {...existing, b: 'bee' }
```

as opposed to

```
const existing = { a: 'ayy' }
const modified = {...existing, ...{ b: 'bee' } }
```

this should be done across the codebase at once, for consistency.

Start by reviewing the linked pull-request comment and searching the codebase for object spreads that wrap additional properties in a second object. Replace each matching pattern with the direct property form, then verify that all such occurrences are consistent and the existing checks still pass.

Written by the indexing model from the issue text.