v0.2.0 (2020-12-04)

• Add rtf_subline, rtf_page_header, rtf_page_footer.
• Add rtf_page to set page related attributes.
• Introduce text_convert argument to allow fixed string.
• Add as_table argument in rtf_footnote and rtf_source to allow footnote
  and datasource inside or outside of a table.
• Refactor pageby feature to enable group_by feature.
  Add vignette\example-pageby.Rmd to illustrate new pageby features.
• Define obj_rtf_border and obj_rtf_text objects to standardize
  border and text attributes.
• Add example ADaM datasets.
• Add validation tracker in \inst folder and testing cases in \test.