Move to w3c WebDriver spec

[lread]

We've been using a capabilities syntax for create session that has long been deprecated. Firefox finally forced our hand with geckodriver 0.35.0, which has removed support for the obsolete syntax.

All supported WebDrivers understand the newer syntax.

We used to pass capabilities in as desiredCapabilities, we now pass them in as a single item in the firstMatch vector. This should match existing behaviour.

Moving to the new capabilities syntax tells chromedriver (and msedgedriver) that we are running in "w3c mode". This has benefits on Etaoin code. Our many customizations for these WebDrivers are no longer necessary, they now support the W3C WebDriver endpoint spec.

In "w3c mode", chromedriver disallows any endpoints that could be served by W3C WebDriver endpoints.

Notable examples are mouse and touch operations. These are now handled by the W3C WebDriver action endpoints. WebDriver actions are not stand-alone, they are submitted as transaction of steps. As such the following Chrome-specific fns are no longer needed and would be confusing if not deleted:

• mouse-btn-down
• mouse-btn-up
• with-mouse-btn
• mouse-move-to (was also available in Firefox)
• mouse-click
• right-click
• left-click
• touch-down
• touch-move
• touch-up

Users will instead express these manipulations via the existing perform-actions.

Fns that represent a transaction of actions in themselves remain:

• drag-and-drop (from element to element)
• double-click* (on an element)
• *-click-on (on an element)
• touch-tap (on an element)

Verifying that everything worked required a full review of the API.

Some sweeping changes:

• Our recent deletion of PhantomJS support allowed me to streamline many defmultis into defns.
• Added links to W3C WebDriver Spec endpoints to docstrings

Added some fns to expose at the W3C WebDriver Spec granularity:

• get-timeouts
• set-timeouts
• get-element-rect
• get-element-rect-el
• get-element-rect
• set-window-rect
• get-window-rect

We have finer grained versions of the above (ex. get-element-position, get-element-size, etc). We've kept these for backwards compatibility, but if we were starting today, we would have just matched today's W3C WebDriver spec.

Minor fixes/changes:

• Uncomment and fix the maximize test
• Screenshots on elements work on safari, enable them
• Added notes on displayedness to docstrings
• Remove internal support for undocumented :desired-capabilities, the implementation was either ultra legacy or misunderstood legacy APIs.

Add bb test-coverage task to check what we are not covering with tests

New tests include coverage for:

• back
• forward
• set-cookie
• release-actions
• *-timeout*
• double-click

Closes #467

Incidentally closes #522 via better docstrings on getting properties.

Closes #484 with W3C WebDriver spec endpoint links.

Please complete and include the following checklist:

• I have read CONTRIBUTING and the Etaoin Developer Guide.

• This PR corresponds to an issue that the Etaoin maintainers have agreed to address.

• This PR contains test(s) to protect against future regressions

• I have updated CHANGELOG.adoc with a description of the addressed issue.