angle option in multipole not documented and new proposal

[rdemaria]

The documentation of the angle attribute is not implemented. The effect is a bit counter-intuitive

mm: multipole, angle=1e-20, tilt=0, knl:={1}, ksl:={0}; ! hkicker negative
mm: multipole, angle=1e-20, tilt=pi/2, knl:={1}, ksl:={0};  !  vkicker negative
mm: multipole, angle=1e-20, tilt=0, knl:={0}, ksl:={1}; ! vertical dipole
mm: multipole, angle=1e-20, tilt=0, knl:={1}, ksl:={1}; ! hkicker negative kick + vertical dipole

I wonder if one could change the implementation and simplify it in such a way:

mm: multipole, angle=1e-20, tilt=0, knl:={1}, ksl:={0}; ! hkicker negative
mm: multipole, angle=1e-20, tilt=pi/2, knl:={1}, ksl:={0};  ! vkicker negative
mm: multipole, angle=1e-20, tilt=0, knl:={0}, ksl:={1}; ! vkicker positive
mm: multipole, angle=1e-20, tilt=0, knl:={1}, ksl:={1}; ! hkicker negative + vkicker positive

In the second implementation angle and tilt fully specify the change of reference frame and knl,ksl only the multipole fields in the tilted frame.

I checked the implementation in twiss only, I have not checked whether track and survey are consistent with twiss.