Added support for Global Styles + various bugfixes

- Support for Tumblr Global Appearance Styles
    - Toggle Title, Description, Header Image
    - Toggle Header Image Stretch
    - Moved Background color to Global styles
- Removed "{if:Show Header Border}"
    - Added "None" option in {select:Header Border Style}
- New "Double" option for {select:Header Border Style}
- Added {select:Navigation Hover Effect} with 4 options (Spread, Raise, Zoom, None)
- Better responsive design
- Panorama posts
- Various other bugfixes