Improves update() method to be able to update from another Struct, and
not overwrite existing Struct attributes, and removes need to
from_dict classmethod.

and use in load_struct

as per expected from dict method.

NO FUNCTIONAL CHANGE

residual_gas_cavity() function updated to calculate residual gas noise of
a single evacuated cavity.

ifo ExcessGas Noise class modified to handle specific case
of Fabry-Perot Michelson.

Simplify newtonian noise calculations to return displacement noise for
simplified configuration: either single test mass or single arm.

new suspension_thermal() function for calculating thermal noise of a
single suspended optic.

ifo SuspensionThermal Noise class modified to handle specific case of
Fabry-Perot Michelson.

substrate_thermoelastic() function updated to calculate thermal noise
of a single suspended optic.

ifo SubstrateThermoElastic Noise class modified to handle specific
case of Fabry-Perot Michelson.

substrate_brownian() function updated to calculate thermal noise of a
single suspended optic.

ifo SubstrateBrownian Noise class modified to handle specific case of
Fabry-Perot Michelson.

substrate_thermorefractive() function updated to calculate thermal
noise of a single suspended optic.

ifo ITMThermoRefractive Noise class modified to handle specific case
of Fabry-Perot Michelson.

substrate_carrierdensity() function updated to calculate thermal noise
of a single suspended optic.

ifo ITMCarrierDensity Noise class modified to handle specific case of
Fabry-Perot Michelson.

new coating_brownian() and coating_thermooptic() functions for
calculating coating thermal noise spectrum for a single optic.

ifo CoatingBrownian and CoatingThermoOptic Noise classes modified to
handle specific case of Fabry-Perot Michelson.

This refactors the seismic noise calculation to be for a single suspension.
The turning of that into a seismic noise spectrum for a LIGO-like IFO is
moved to the Seismic(nb.Noise) class definition in the ifo module,
effectively separating fundamental seismic noise calculation from assumptions
of experimental configuration.

susQuad function take sus Struct instead of full ifo

swap out deprecated interface

This allows for direct comparison between py and mat gwinc.

This fixes a regression in the move to the new Budget structured. The keys
in the gwinc() noises output changed to be the name of the Noise class,
instead of the label, causing the matgwinc comparison test to fail.

This fixes the keys in the gwinc noises output to be the labels to maintain
consistency.

Fix suspension: silicon blade spring

2 um wavelength

Seismic and Newtonian parameters