Marked the editor instance as a raw object

[psmyrek]

Suggested merge commit message (convention)

Fix: Marked the editor instance this.instance as a raw object so that it will never be converted to a proxy. Closes #203.

Internal: Renamed the internal properties and methods: $_instance -> instance, $_lastEditorData -> lastEditorData and $_setUpEditorEvents() -> setUpEditorEvents().

Internal: Bumped dev dependencies.

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Additional information

For example – encountered issues, assumptions you had to make, other affected tickets, etc.

[coveralls]

Pull Request Test Coverage Report for Build 236

• 11 of 11 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 230:	0.0%
Covered Lines:	34
Relevant Lines:	34

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💛 - Coveralls

[przemyslaw-zan]

LGTM & WFM