Avoid creating decorators for class declared as abstract
Added modified_parameters property to Specifications

Working by testing parameter values for equality with the default
values. Includes the first dictionary comprehension committed in
Topographica (Python 2.7+).
Small formatting fix to summary method output
Added modified_parameters property to Model and added missing docstring
Made Model __str__ and _repr_pretty_ more consistent with Specifications
Added modifications method to Model to list all parameter modifications
Fixed Pyflakes warnings
Updated pyflakes script to skip method redefinition warnings

Warnings are printed but not counted as errors for any redefinitions in
the topo/submodels directory.
Renamed ObjectClass decorator generator to ClassDecorator
Updated param submodule reference
The param_logging_level context manager has been moved to param
Removed ordering hacks by supplying order_projections function instead
Improved readability of V1_afferent_projections method
Class-based models now use time-dependent behaviour by default
Renamed 'update_parameters' to 'update' with small signature change
Renamed 'settings' helper method to 'params'
Updated param submodule reference
Fixed outdated name for param logging context manager
Added ExamplesGCAL class for legacy support and updated ty file