Sable Drydock 3.64: changes since 2.49

• The manager is redesigned: fixed UI scale, new pixel font, right tool column, readout strip, hover preview card, collapsible list, context menu.
• Projections panel (hold X or drag a point): front, side and top views, zoom, linked lines, two-axis point dragging, depth slice in 1-block steps.
• Undo and redo (Ctrl+Z, Ctrl+Y) for moves, points, joints, visibility, renames, scale, mass and origin.
• Ctrl+Y also re-welds the same pair with the same points and joint type.
• Levels tree: rigidly welded levels form nodes; per-player favourite groups; unloaded levels are shown.
• Schematics: World and Schematics tabs, save to schematic, opened files can be placed at once. Photomancy is no longer required. Welds still require Synaxis.
• Scale and Mass window: tabs no longer mix, the window remembers its position.
• Fixed: a sub-level whose weld was removed stayed in the vehicle group in the manager list.
• Performance: cheaper ray clips, spatial index of sub-level bounds, constraint validity check every 20 ticks.
• For mods: public API for top-bar modes and a widget toolkit; tools can add panels to the manager and outside it.