Identifier is now a simple counting up number

Replaces `+new Date()`.
It is safer for the case if instances are initialized at the same time.
Merge pull request #89 from andreruffert/simplifies-instance-identifier

Identifier is now a simple counting up number
Allow 0 value for pageX
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)
chore(grunt): introduce `grunt release` task

A task to simplify the release process:
* version bump
* codename generation
* build
* commit
chore(release): v0.3.4
Merge pull request #94 from andreruffert/release-0.3.4

chore(release): v0.3.4
chore(grunt): consider rangeslider.jquery.json

We now consider rangeslider.jquery.json in the grunt release task.
* version bump
* commit
merge: develop into consider-hidden-elements
fix: floation point rounding issue

Change `getValueFromPosition` value calculation.
The `+ this.min` needs to be outside, otherwise it gets the wrong
answer unless `this.min` is divisible by this.step.
Big ups to @jpmckinney

Closes issue #50, #91
Merge pull request #95 from andreruffert/fix-floating-point-rounding-issue

fix: floation point rounding issue
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
chore(release): v0.3.5
Merge pull request #96 from andreruffert/release-0.3.5

release: 0.3.5