Update logic to factor other form fields

[Mathachew]

Update Autotab's behavior for other form fields.

• Skip hidden fields, even if they're in a selector, like :input
• Select list
  • Auto tab backwards when backspace is pressed
  • Auto tab forward when a value is selected (configurable)
• Multiple select list, Button, Checkbox / Radio button
  • Auto tab backwards when backspace is pressed
  • Do nothing when selected/clicked/ticked
• Textarea
  • Auto tab backwards when backspace is pressed and the textarea is empty
  • Explore options of establishing a maxLength and enforcing it in browsers that don't support it (IE9 and below, Opera). If Autotab is able to effectively support this, then auto tab when the max length is reached. If not, then proceed with normal behavior.

[Panman82]

In relation to Issue #23, perhaps the logic to determine next/previous tab fields could be extended look at the forms fields. I've see some example code that iterates through an input.form.elements array to determine which field to tab to next. I can dig that up again if you'd like. Might be useful to automatically connect different "autotab groups".

[Mathachew]

@Panman8201 I've updated #23 with my thoughts on it. This enhancement is to improve the current behavior. I honestly haven't tested against other field types, and for a while was using an :input selector in my usage examples without realizing hidden fields were included.

[Mathachew]

v1.7.0 has added support for other form fields.