Runtime dispatch with ft_fix_before

[roflmaostc]

Hi,

@RainerHeintzmann there is a couple of runtime dispatches because of type-instability.

See this:

FourierTools.jl/src/fourier_resizing.jl

Line 147 in 000735e

mat = FourierJoin(mat, d, L1)

I think you probably should always return the FourierJoin type, otherwise it can't handle it.

This causes actually some issues with slow packaging loading times.

[roflmaostc]

This affects also rft_pad, rft_fix_after.

[roflmaostc]

I used this tool: https://aviatesk.github.io/JET.jl/stable/tutorial/

@report_opt ignored_modules=(AnyFrameModule(Base),) resample(x, (2,2))

[RainerHeintzmann]

Ok. Will see if I can fix this.

[roflmaostc]

fixed by #30