ParameterCollection and supporting classes requre extension and updates
## Additional parameter types
- File and Folder selection
- selection from the set of options (list parameter)
- should options be strings or any arbitrary type?
- array parameter?
## XML reader and writer for ParameterCollection
## GUI support:
- auto-generate GUI panel element for each ParameterCollection item
- make a function getParameterPanelCollection
- ?make some parameters invisible in GUI by defining GUI visibility tag for each parameter
## Create usage examples
issue