Textcontent fix

This fix resolved the `text_content` warning. Also cleaned up some missing params from documentation that showed up in `check_doc()`. Also added `ggplot2` to Import list since `plot_to_filename` requires it. If anyone wants to install from this branch and looks things over before merging with master that would be great. Otherwise I'll do it after testing things out for a few days. Everything works at my end and all checks pass.