Restore HTML generating functions

These functions were temporarily ripped out of Shiny and moved
to the htmltools package. We've discovered that it's safe to
keep including them in shiny; as long as the functions in shiny
and the functions in htmltools are identical, the user won't
receive a conflict warning.

inst/staticdocs/index.r

@@ -67,6 +67,18 @@ sd_section("UI Outputs",
     "downloadButton"
   )
 )
+sd_section("Interface builder functions",
+  "A sub-library for writing HTML using R functions. These functions form the foundation on which the higher level user interface functions are built, and can also be used in your Shiny UI to provide custom HTML, CSS, and JavaScript.",
+  c(
+    "builder",
+    "HTML",
+    "include",
+    "singleton",
+    "tag",
+    "validateCssUnit",
+    "withTags"
+  )
+)
 sd_section("Rendering functions",
   "Functions that you use in your application's server side code, assigning them to outputs that appear in your user interface.",
   c(
@@ -147,7 +159,6 @@ sd_section("Embedding",
   "Functions that are intended for third-party packages that embed Shiny applications.",
   c(
     "shinyApp",
-    "maskReactiveContext",
-    "knitr_methods"
+    "maskReactiveContext"
   )
 )