Dialog button style individually configurable

[Thodor12]

Currently it's not possible to separately style the close and done buttons.
In my application I'm consistently holding to a "error" style for cancel buttons and a "primary" style for completion/save buttons.
This is not doable if there's only 1 property available for setting the style for both buttons.

Suggested changes:

• Introduce separate properties for the done and close buttons
• Rename matching text properties to refer to "dialog" instead of "modal", to match other properties
• Thanks to prettier some formatting related things have been changed (blame prettier)

! This is a breaking change

[Thodor12]

Superseded by #33