Refactored code to support local and external material sources
This is the first PR in a series to support external modules. External
modules allow materials to be stored in external data sources such as
databases or web services. No new functionality is introduced in this
PR, rather it is a refactoring of code that will allow for changes to
be introduced in future PRs. Minor performance improvements have also
been made in the model and material managers.
The Python API has been enhanced for many data types to allow for
modification within Python.
Rework of the material handling system.
This first part concntrates on a rework of the material cards.
Rather than use a fixed list of possible properties, properties can
be defined separately in their own files and mixed to provide a
complete list of possible properties. Properties can be inherited.
The cards then provide values for the properties. These can also
be inherited allowing for small changes in cards as required.
The new property definitions are more extensive than previously.
2 and 3 dimensional arrays of properties can be defined. Values
are obtained by calling an API instead of reading from a dictionary.
For compatibility, a Python dictionary of values can be obtained
similar to how it was done previously, but this is considered a
deprecated API and won't support the newer advanced features.
The editor is completely reworked. It will be able to edit older format
material cards, but can only save them in the new format.
For testing during the development phase, a system preference can
specifiy wether the old or new material editors are to be used. This
option will be removed before release.
