Add more region styling options

Currently we have two region style options in the theme settings, Panel and Block. But these currently only provide the default modifiers without any customization. Let's add the following options:

Block

Style modifiers

See block modifiers.

• Default
• Muted
• Primary
• Secondary

Padding

• Remove padding using any of the utility classes
• Large padding using the block uk-block-large class

Panel

Style modifiers

See panel modifiers.

• Default panel box
• Primary panel box
• Secondary panel box
• Hover panel
• Panel space
• Panel divider