Change snapping behavior to snap strip edges when they are close to snap point. Default behavior is, that each transformed strip is snapped to any other strip. Implement snapping controls in sequencer tool settings. These controls include: - Snapping on/off - Ability to snap to playhead and strip hold offset points - Filter snap points by excluding sound or muted strips - Control snapping distance Snapping controls are placed in timeline header similar to 3D viewport Reviewed By: mano-wii Differential Revision: https://developer.blender.org/D11646