Replace variables with numbers after optimisation

src/build_sequences.jl

src/building_blocks.jl

src/gradients/changing_gradient_blocks.jl

src/gradients/constant_gradient_blocks.jl

src/overlapping/spoilt_slice_selects.jl

src/overlapping/trapezoid_gradients.jl

src/pulses/constant_pulses.jl

src/pulses/instant_pulses.jl

src/pulses/sinc_pulses.jl

src/readouts/instant_readouts.jl

src/sequences.jl