Navbar items

Branch contains setter and getter methods for the following navigation items:

• source_code (add remove button to show RMD code or as hyperlink)
• social_links (links to social media)
• method add_to_navbar: adding custom link to the navigation bar.

PROBLEM: The method add_to_navbar is not finished, because the creation of the following YAML structure required by flexdashboard is missing (probably not possible with the package ymlthis) (https://rmarkdown.rstudio.com/flexdashboard/using.html#navigation_bar)

---
title: "Navigation Bar"
output: 
  flexdashboard::flex_dashboard:
    navbar:
      - { title: "About", href: "https://example.com/about", align: left }
---

R/AllGenerics.R

@@ -45,4 +45,22 @@ setGeneric("theme<-", function(dashboard, value) standardGeneric("theme<-"))
 setGeneric("datadir", function(dashboard) standardGeneric("datadir"))
 
 #' @export
-setGeneric("datadir<-", function(dashboard, value) standardGeneric("datadir<-"))
\ No newline at end of file
+setGeneric("datadir<-", function(dashboard, value) standardGeneric("datadir<-"))
+
+#' @export
+setGeneric("social_links", function(dashboard) standardGeneric("social_links"))
+
+#' @export
+setGeneric("social_links<-", function(dashboard, value) standardGeneric("social_links<-"))
+
+#' @export
+setGeneric("embed_source<-", function(dashboard, value) standardGeneric("embed_source<-"))
+
+#' @export
+setGeneric("source", function(dashboard) standardGeneric("source"))
+
+#' @export
+setGeneric("source<-", function(dashboard, value) standardGeneric("source<-"))
+
+#' @export
+setGeneric("add_link", function(dashboard, ...) standardGeneric("add_link"))
\ No newline at end of file