Improvement of RF frequency control

[lfarv]

The get_acceptance function is an example of a function which may internally modify the ring RF frequency, to satisfy its dp or dct argument. The new frequency_control decorator avoids this and offers a cleaner solution to handle dp and dct in future similar functions.

This decorator can be applied to any function like func(ring, *args, **kwargs). Example:

@frequency_control
def get_acceptance(ring, planes, npoints, amplitudes, nturns=1024,
                   refpts=None, dp=None, offset=None, bounds=None,
                   grid_mode=GridMode.RADIAL, use_mp=False, verbose=True,
                   start_method=None, divider=2, shift_zero=1.0e-9):

It looks at the 1st argument of the decorated function, which must be a Lattice object (ring)

• if ring.radiation is True and dp or dct is specified, it makes a copy of ring with a modified RF frequency, removes the dp and dct keywords and call the decorated function with the copy of ring,
• otherwise, it directly calls the decorated function with the initial arguments.

So the decorated function does not need to care about RF frequency: It uses ring as it is, the dp or dct arguments will be present only when they are allowed (in 4D only).

In addition, get_revolution_frequency is improved when dp is specified: rather that relying on the momentum compaction factor, it uses closed orbit computation, giving a more accurate result.

[lfarv]

The same improvement on off-momentum revolution frequency is done in Matlab, so I rename the all request.

[swhite2401]

Seems like a very nice improvement