Implementation for several tasks in Design: Animation Editors UI Redesign
This patch
- Centers Animation Editor Headers' Pivot Point, Frame Snapping, & Proportional Editing buttons to match other Editors.
- Makes Frame-Snapping popover consistent with other icon-only popovers
- Removes redundant SACTSNAP_STEP and SACTSNAP_TSTEP Snapping Modes
- Reduces 'Use Normalization' toggle to Icon and groups it with other toggles.
- Moves less-important 'Use Auto-Normalization' toggle to Channel menu