This function returns the GUI setup results by calling shinyApp.
Primarily, this is only useful when hosting the application publicly, such as
through http://www.shinyapps.io/. The function mirtCAT_preamble must be
run before this function is called. The object is executed by calling runApp.
Usage
createShinyGUI(ui = NULL)
Arguments
ui
a shiny UI function used to define the interface. If NULL, the default one will be used.
See mirtCAT:::default_UI for the internal code