This change is required to support copies of the same cast member running in different channels.
* DIRECTOR: Move widget ownership from cast member to channel
* DIRECTOR: Cache cast dimensions from createWidget
* DIRECTOR: Add null checks for createWidget
* GRAPHICS: MACGUI: Clear active/hover WM references if the widget is destroyed
* DIRECTOR: LINGO: Re-add null check for kTheEditableText
* DIRECTOR: Avoid destroying widgets if the channel isn't dirty
* DIRECTOR: Fix dirty test
* DIRECTOR: Fix text field writeback
* DIRECTOR: Fix null cast check
* DIRECTOR: Add bbox as argument to createWidget
* DIRECTOR: Add setCast method to Channel
* DIRECTOR: Fix use-after-free in Channel::getMask
* DIRECTOR: Fix bounding box for Button sprites
* DIRECTOR: Cache widget dimensions in cast member
* DIRECTOR: Remove widget from channel if nextSprite is empty
* GRAPHICS: MACGUI: Fix MacText::splitString for empty string case
* DIRECTOR: Add null checks for movie and score in processEvents
The Director engine, for which I introduced this setting, has also been updated.
To account for different ink types, the background colour will be applied in the
blitting step, and each text chunk keeps its own palette information.
