Refactored: works for multiple password inputs, fixes regarding autofill…

[slackero]

• Works with multiple input[type=password].
• The aria-label of the toggle button can be customized adding data-show and data-hide attributes to the password input.
• The toggle button is added by JavaScript — remove existing <button> tags when upgrading.
• The toggle button is always visible.
• Fixes the problem that the toggle icon can be hidden when autofill is active.
• Added aria-pressed attribute to the toggle button.
• Added jQuery compatible script.
• Updated, added demos.