Add vertical boxes support

[vinkla]

It would be nice if we could have the option to customize the boxes like this:

[frozzare]

Yeah, that would be nice. When doing this it's important to test so all properties looks good, testing the different layout options for properties that has this setting, for example flexible and repeater.

[frozzare]

This will be out in v3.1.0. You can set this on box and property level. All properties will inherit it from the box if the default value isn't matched. Setting a property to horizontal (with sidebar) layout when the box has vertical layout will not work.

Box:

$this->box( [
  'title'  => 'Content',
  'layout' => 'vertical'
], [] );

Property:

papi_property( [
  'title'  => 'Name',
  'type'   => 'string',
  'layout' => 'vertical'
] );

[vinkla]