Use more generic collections.abc.Mapping to detect a nested dict.

since it's not needed for most operations

implement as __main__ for `gwinc.ifo`

also add to CI.  closes #48

This allows for specifying an order that makes sense without too much loss
of ease of expandability (just need to add an entry to a list).

This finally gets rid of the whole precompIFO function.  It does this
by breaking up precomp into various smaller functions, moving them
into the common IFO noise definition module, and using them
appropriately when needed.  This does result in some of the functions
being called multiple times in the full budget calculation for the
aLIGO-like budgets, but the cost should be minor given the convenience
of getting rid of the whole precomp thing, thereby opening up
everything to non-aLIGO-like configurations.

Even though some functions are calculated multiple times, we're still
orders of magnitude faster than matgwinc, so...  Should still revisit
down the line though.

closes #40

Define new Strain(nb.Calibration) and apply it to all canonical ifo budgets.

Also supports a Budget.calibrations attribute that lists calibrations to be
applied to all noises.

Allows for specifying as a class attribute.

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

all test will pass again after this commit

For some reason these noises were just dividing by L**2 to convert to
strain, rather than using the dhdl conversion.

This changes the noises for Voyager and CE2, so the tests fail, and
the IFO caches should be updated when this is merged.

Drop specific comparison to MATGWINC output and move to comparisons to
cached hdf5 traces.  Comparisons to all cached IFO traces will be done by
default.  A PDF report of all discrepancies for all IFOs will be
generated if requested.  inspiral ranges will be calculated if the
inspiral_range package is available.

This adds trace caches (in git-lfs) for all currently supported IFOs,
effectively snap-shotting the current state of the repo.

gitlab CI also updated to use new tests

Should cover/simplify the most common use case, equivalent to running:

load()
update(**kwargs)
calc_traces

Needs to be implemented.