create_metamodelBuiltin
                        Run 'modelBuilderUI()' and create resulting
                        metamodel
create_metamodelTextual
                        Send metamodel to 'modelTextualUI()' and run
                        shiny application
estimatesUI             Shiny GUI to examine the model and evaluate
                        estimates for fixed effects.
modelBuilderUI          Build RsNLME model from Shiny GUI and generate
                        corresponding RsNLME code
modelTextualUI          Edit textual RsNLME model from Shiny GUI
