Align Linter Rules with WordPress.com

[jkmassel]

This PR reformats the code base in order to be accepted by the WordPress.com linter.

It makes the following syntactic changes (but no functional changes):

• Uses Yoda conditions for comparison
• Adds visibility specifiers to every method
• Converts all methods to snake_case

[codeclimate[bot]]

Code Climate has analyzed commit a1c54baa and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 99.5% (50% is the threshold).

This pull request will bring the total coverage in the repository to 99.0% (0.0% change).

View more on Code Climate.