feature: add `isHidden` method

Checks if a `element` is visible in the DOM

Issue: Consider initialization and update of hidden Elements (#88)
feature: add `getHiddenParentNodes` method

Gets hidden parentNodes of an `element`.

Issue: Consider initialization and update of hidden Elements (#88)
feature: add `getDimensions` method

Returns dimensions for an element even if it is not visible in the DOM.

Issue: Consider initialization and update of hidden Elements (#88)
feature: getDimensions for setting handle,range width

Issue: Consider initialization and update of hidden Elements (#88)
example: initialisation on hidden elements

Issue: Consider initialization and update of hidden Elements (#88)
build: :boom:

Issue: Consider initialization and update of hidden Elements (#88)
merge: develop into consider-hidden-elements
merge: develop into consider-hidden-elements
Merge branch 'consider-hidden-elements' into develop

* consider-hidden-elements:
  build: :boom:
  example: initialisation on hidden elements
  feature: getDimensions for setting handle,range width
  feature: add `getDimensions` method
  feature: add `getHiddenParentNodes` method
  feature: add `isHidden` method