Improve portrait positions and position event

[Jowan-Spooner]

• Make portrait positions be referenced by name (string).
• PortraitContainers can have a list of "names"
• improve VN portrait layer (better spacing)
• improve Shortcode Event save/load code.
  • can now Save, whether a shortcode had been set.
• allow shortcode values to contain = but not unescaped "
• Implement multitween (allowing multiple tweens to contribute to the same property)
• Implement container movement, rotation and resizing
• Add "position-suggestions" field in Portrait settings
• Improve position event
  • adds translation, rotation, resize
  • adds tweening settings (ease/trans/await)
• Add a debug draw mode for PortraitContainers