Render functions can be inserted directly into .Rmd

All render functions need to call markRenderFunction on their
return values for this mechanism to work.

Also:
- Remove runRmdContainer (it's moved to rmarkdown)
- Remove some bad .Rbuildignore entries
- Make height/width in shinyApp respected

.Rbuildignore

@@ -10,5 +10,3 @@
 ^man-roxygen$
 ^\.travis\.yml$
 ^staticdocs$
-^R/.*\.Rmd1$
-^R/.*\.html$