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/assemble.R

@@ -27,21 +27,23 @@ setMethod("assemble", "i2dashboard", function(dashboard, pages = names(dashboard
   ymlthis::yml(date = F) %>%
     ymlthis::yml_title(dashboard@title) %>%
     ymlthis::yml_author(dashboard@author) %>%
-    ymlthis::yml_output(flexdashboard::flex_dashboard(theme = dashboard@theme)) %>%
-    {if(dashboard@interactive) ymlthis::yml_runtime(., runtime = "shiny") else .} -> yml_header
+    ymlthis::yml_output(flexdashboard::flex_dashboard(theme = "yeti")) -> yaml_header
+
+  # workaround, because variable "dashboard@theme" was not recognised
+  yaml_header$output$`flexdashboard::flex_dashboard`$theme <- dashboard@theme
+  if(dashboard@interactive) yaml_header <- ymlthis::yml_runtime(yaml_header, runtime = "shiny")
 
   # add source_code to yaml_header
   if(source_settings$source){
-    yml_header$output$`flexdashboard::flex_dashboard`$source_code <- source_settings$value
+    yaml_header$output$`flexdashboard::flex_dashboard`$source_code <- source_settings$value
   }
 
   # add social_links to yaml_header
   if(length(dashboard@social_links) > 0){
-    yml_header$output$`flexdashboard::flex_dashboard`$social <- dashboard@social_links
+    yaml_header$output$`flexdashboard::flex_dashboard`$social <- dashboard@social_links
   }
-  print(yml_header)
 
-  yml_header %>%
+  yaml_header %>%
     ymlthis::use_rmarkdown(path = tmp_document, include_body = FALSE, quiet = TRUE, open_doc = FALSE)
 
   # Add i2dash global setup