Add inputs to a trelliscope display

Usage

add_inputs(trdf, ..., email = NULL, vars = NULL)

trdf: A trelliscope data frame created with as_trelliscope_df() or a data frame which will be cast as such.
...: Any number of input specifications. These can be specified with any of input_number(), input_radio(), input_checkbox(), input_select(), input_multiselect(), input_text()
email: An email address (optional).
vars: A vector of meta variable names found in the display. These will be made available as columns in the csv download of user inputs.