Update AddToMathlib.lean, Vector.lean, Line.lean and Position/Angle.lean

[mbkybky]

@jjdishere Main Changes: AddToMathlib.lean :

• Finish the part of the compatibility among group, AddTorsor and order

Vector.lean :

• Realize Dir as a circular ordered AddTorsor

Line.lean :

1. Realize a directed line as a linearly ordered AddTorsor
2. Add induction principles to deduce results for directed lines or lines from those for rays
3. Add some theorems about DirLine.ddist and fix some theorems

Position/Angle.lean :

• Changed the definition of Angle. Now an angle is determined by a vertex and two directions.