For many constraints, to ensure the sketch doesn't flip-flop between multiple stable states (e.g. pentagon vs five-pointed star), we need such constraints to preserve chirality. We will also need to infer chirality from 2.x sketches when loading old files.

The list of constraints is:

• PROJ_PT_DISTANCE
• PT_LINE_DISTANCE
• PT_PLANE_DISTANCE
• PT_FACE_DISTANCE
• SYMMETRIC
• SYMMETRIC_HORIZ
• SYMMETRIC_VERT
• SYMMETRIC_LINE
• HORIZONTAL
• VERTICAL
• PERPENDICULAR
• ANGLE
• ARC_LINE_TANGENT
• CUBIC_LINE_TANGENT
• CURVE_CURVE_TANGENT
• PARALLEL

Depends on #75 as I would like to avoid adding new options to the old file format.