* should resolve BreakingBytes#9 Fields layer (altho not really a layer)
* add Field base class to core
* add test_field to test_core to see if a class constructor works
* add new test_fields to carousel.tests to try to make a data class using fields

* consistent with parameters in each layer
* subclass to dict, easier than trying to reimplement dict, or change a lot of code, since all of the layers are already expecting parameters to be a dictionary
* do not create any attributes in Parameter, only dictionary items (if this changes later, make sure not to clash with members already defined in dict)
* add __repr__ method since dictionary is ugly
* add extras to collect items not in attributes (metadata)
* fix test_fields in test_core to use __getitem__ since it's a dict, instead of __getattribute__, aka getattr() as if it were an object class only
* fix comparison of velocity data elapsed_time was using wrong key for assertion comparison.

* use DataParameter in tests
* use [f for f in get_fields(include_parents=False) if not f.auto_created)] to filter out auto created and related fields
* so don't need to import AutoField
* finally complete todo's in registry, just generate reg attrs from meta_names, can remove __init__(self) from most layers
* allow _private meta-names, why not?
* update docs
* in CommonBase set_param_file_or_parameters() only get Parameters
* add DataParameter class in data_sources and FormulaParameter to formulas
* remove test_field from test_core

* add layer parameter classes, set _attrs
* if calc dependency is string, make it a list
* convert unc to percent
* remove field todo's in outputs

* address BreakingBytes#43 all readers use same format
* update docs a little
* also have to fix apply units to cached data
* fix param_file must apply DataParameter to each item
* all test_data passsing! but need to add test for cached data!

* meta is Meta class, so module, package and path are attributes of it, not items

* closes BreakingBytes#64 - formulas are separated, no more formula keyword, all formulas are in parameters
* addresses BreakingBytes#62 - formulas use Meta for module, package and path
* adresses BreakingBytes#40 - very similar to BreakingBytes#62, but now formulas has Meta too
* closed BreakingBytes#6 - use meta_names to instantiate attributes for registries, this actually already happened in a recent commit
* extract Meta from parameter files if it's there using type("Meta", (), file_params.pop('Meta')) pretty easy
* read in formulas from param file as FormulaParameters instead of just dictionaries
* fix some of the pvpower example files: newstyle model and formula json files

* remove formulas base constant _importer_attr, don't pop importer and don't set it
* in Formula, remove class formula importer class attribute, then check _meta for importer, and if None, set it to PyModuleImporter
* now formula importer is in _meta
* update tests in test_formula()
* in expression importer, 'expression' is in ['extras']

* this is a HACK! need to get simulations to work with parameters, but to much work to implement BreakingBytes#71
* sim parameter attributes are the simulation arguments
* settings arg used to select which set of sim args to use, if not given use first.
* update test_sim PythagorasSim() and Sandia_perfmod_newstyle

* convert outputs param file to dict of OutputParameter
* convert simulation param file to SimParameter settings, use file name minus extension for settings name
* deprecated sim attributes will be in extras
* update tests and sandia_perfmod_newstyle with OutputParameter and SimParameter

* fix uncertainty static calc conversion to percent is multiply by 100 (NOT divide st00pid)
* don't use CalcParameter yet, too much work, but leave it partially implemented, instead fake parameters in the constructor by getting the class attributes
* for test calc metaclass to pass, compare test1 to test2 instead of vv, since test 2 now has extra fields that are set by default, like "dynamic": [], that test1 doesn't have
* fix c_unc in comparison, array is unnecessary, get float64 using item(), since only one value

* the snippet was removed since it's now obsolete - the new Django Meta
 o\Options API has new methods, _eg_: `get_fields()`, to get fields, to
 filter out parent, autogenerated and reverse fields from a model
* add new comment that links to new Django Meta Options API