move load_struct logic into Struct.from_file() class method, and remove
load_struct function.

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.

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