Outstanding issues from processing redevelopment

[ccrook]

• Build automated test suite
• Add options for storing as 3d features with Z, ZM
• Add rendering options to processing - maybe as second processing algorithm
• Add support for adding layer properties to processing generated layers in the same way as the dialog (note that properly this needs getting the source layer name where defined)
• Duplicate point value - should not recalculate for every incremental change of value in dialog.
• Enum parameters currently passed as integers. Would be much better for the future if passed as string codes such as 'quantile','fixed', etc