New features

• Added hidden event that is emitted when the picker is hidden (thanks @jmlee2k)
• Added the ability to switch themes after constructing the picker (thanks @jmlee2k)

Bug fixes

• Fixed error when hiding picker after showing in mobile mode (thanks @jmlee2k)
• Fixed wrong category being highlighted when the picker is first shown in some browsers (#93)
• Fixed picker not hiding immediately when animations are disabled in some browsers (#92)
• Fixed focus stealing when hiding picker in some browsers (#91)
• Fixed picker alternating position over/under target (#90)
• Fixed jumping scroll position on some browsers (#87)