Merge branch 'refactor-sub-budgets' into 'master'

gwinc/ifo/Aplus/__init__.py

gwinc/ifo/CE1/__init__.py

gwinc/ifo/CE2silica/__init__.py

gwinc/ifo/CE2silicon/__init__.py

gwinc/ifo/Voyager/__init__.py

gwinc/ifo/aLIGO/__init__.py

gwinc/ifo/noises.py

gwinc/noise/coatingthermal.py

gwinc/noise/newtonian.py

gwinc/noise/quantum.py

gwinc/noise/residualgas.py

gwinc/noise/seismic.py

gwinc/noise/substratethermal.py

gwinc/noise/suspensionthermal.py

test/budgets/test_budgets.py

test/inherit/subdir/CustomBudget/__init__.py

test/inherit/test_inherit.py