Video Remixer: Allow for multiple block hints per scene

[jhogsett]

Add support for adding more than a single Block processing hint. They are separated with commas like all processing hints, and are processed in the order they appear.

• This is necessary because, if using Block FX to obscure content that shouldn't be shown, often there are several places in the scene that need blocking

Also, add support for "Sticky" Block Hints. Follow the Block hint type with ! to make it stick until stopped.

• This is necessary because, if using Block FX to obscure constant content, such as a company logo, it should not be necessary to add that block to each scene
• Examples:
  • Block a face in the center square of the scene with pixelation; also block the lower-right square with pixelation beginning with this scene and appearing until stopped: {B:X5/9,X!9/9}
  • Cancel Sticky Block Hints starting with the next scene after this one: {B:!} (place the cancel hint in the last scene the sticky hint should appear)