new df_print option: theme-styled data frame tables by default (kable)

Change-Id: I827aa1c5f372ee78944a8bd32f51caea1731e87f
diff --git a/R/revealjs_presentation.R b/R/revealjs_presentation.R
index ec8a814..68d0733 100644
--- a/R/revealjs_presentation.R
+++ b/R/revealjs_presentation.R
@@ -186,6 +186,13 @@
 #'   `c("notes", "search", "menu", "zoom")`; pass `NULL` to render without
 #'   any plugins. Note that `self_contained` must be set to `FALSE` in order
 #'   to use Reveal plugins.
+#' @param df_print Method used to print data frames in the document. The
+#'   default, `"kable"`, renders data frames as plain HTML tables styled by
+#'   the presentation theme, so that results look reasonable on slides without
+#'   any extra code. Since `"kable"` prints all rows, consider showing only
+#'   `head(x)` on slides with many-rowed results. Other supported methods are
+#'   `"default"` (plain text output), `"tibble"`, and `"paged"` (an
+#'   interactive paged table, see [rmarkdown::html_document()]).
 #' @param template Pandoc template to use for rendering. Pass "default" to use
 #'   the rmarkdown package default template; pass `NULL` to use pandoc's
 #'   built-in template; pass a path to use a custom template that you've
@@ -228,6 +235,7 @@
                                   reveal_options = NULL,
                                   reveal_plugins = c("notes", "search", "menu", "zoom"),
                                   highlight = "default",
+                                  df_print = "kable",
                                   mathjax = "default",
                                   template = "default",
                                   css = NULL,
@@ -457,6 +465,7 @@
     ),
     keep_md = keep_md,
     clean_supporting = self_contained,
+    df_print = df_print,
     pre_processor = pre_processor,
     post_processor = post_processor,
     base_format = html_document_base(