Readability: clean up indentation.
Readability: [more] consistent use of blank lines; remove or add trailing blank(s).
Consistent variable ordering; remove unused 'empty' member variable; rename ctl_env to defaultModulePath and initialize inline, eliminating initKnob member variable and instead using makeKnobs() member function for a runtime test.
Inject a little ILM style: no virtual qualifier in implementation files on virtual methods.
Use knob_changed() more in the style of the examples in the NDK documentation.
Promote user_module_paths to NukeCtlIop member variable, and various path- and transform-reading functions in the global namespace to member functions.
Fix from Matt Plec of the Foundry for handling Set Module Path and Module Path controls.
Add check for ShowPanel event.