added new_tab to cell_spec
diff --git a/R/cell_spec.R b/R/cell_spec.R
index faaf85b..8e3facc 100644
--- a/R/cell_spec.R
+++ b/R/cell_spec.R
@@ -36,6 +36,7 @@
 #' bootstrap module manually. Read the package vignette to see how.
 #' @param link A vector of strings for url links. Can be used together with
 #' tooltip and popover.
+#' @param new_tab T/F for whether to open up the new link in new tab.
 #' @param extra_css Extra css text to be passed into the cell
 #' @param escape T/F value showing whether special characters should be escaped.
 #' @param background_as_tile T/F value indicating if you want to have round
@@ -52,7 +53,7 @@
                       color = NULL, background = NULL,
                       align = NULL, font_size = NULL, angle = NULL,
                       tooltip = NULL, popover = NULL, link = NULL,
-                      extra_css = NULL,
+                      new_tab = FALSE, extra_css = NULL,
                       escape = TRUE,
                       background_as_tile = TRUE,
                       latex_background_in_cell = TRUE) {
@@ -68,7 +69,7 @@
   if (tolower(format) == "html") {
     return(cell_spec_html(x, bold, italic, monospace, underline, strikeout,
                           color, background, align, font_size, angle,
-                          tooltip, popover, link, extra_css,
+                          tooltip, popover, link, new_tab, extra_css,
                           escape, background_as_tile))
   }
   if (tolower(format) == "latex") {
@@ -80,7 +81,7 @@
 
 cell_spec_html <- function(x, bold, italic, monospace, underline, strikeout,
                            color, background, align, font_size, angle,
-                           tooltip, popover, link, extra_css,
+                           tooltip, popover, link, new_tab, extra_css,
                            escape, background_as_tile) {
   if (escape) x <- escape_html(x)
   cell_style <- NULL
@@ -127,7 +128,12 @@
   }
 
   if (!is.null(link)) {
-    x <- paste0('<a href="', link, '" style="', cell_style, '" ',
+    if (new_tab) {
+      target_blank = 'target="_blank" '
+    } else {
+      target_blank = NULL
+    }
+    x <- paste0('<a href="', link, '" style="', cell_style, '" ', target_blank,
                 tooltip_n_popover, '>', x, '</a>')
   } else {
     x <- paste0('<span style="', cell_style, '" ',
@@ -193,13 +199,13 @@
                       color = NULL, background = NULL,
                       align = NULL, font_size = NULL, angle = NULL,
                       tooltip = NULL, popover = NULL, link = NULL,
-                      extra_css = NULL,
+                      new_tab = FALSE, extra_css = NULL,
                       escape = TRUE,
                       background_as_tile = TRUE,
                       latex_background_in_cell = FALSE) {
   cell_spec(x, format, bold, italic, monospace, underline, strikeout,
             color, background, align,
-            font_size, angle, tooltip, popover, link,
+            font_size, angle, tooltip, popover, link, new_tab,
             extra_css, escape, background_as_tile,
             latex_background_in_cell)
 }