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