I found a solution. I deleted the whisker folder in ~My Documents\R\win-library\3.0\ and reinstalled the package. Everything worked.
Thanks to Winston Chang who made me realize that my devtools problems were coming from the whisker package which I believe devtools relies on. Thank you to @DWin who gave me the idea of chucking out a malfunctioning library and reinstalling the library.
It was when I issued library(whisker)
that I realized the problem may not be with devtools at all but rather with whisker
> library(whisker)
Error in namespaceExport(ns, exports) :
undefined exports: iteratelist, rowSplit, whisker.escape, whisker.render
Error: package or namespace load failed for ‘whisker’
I can now load devtools and whisker.
It is odd. I would have thought that my packages would have been reinstalled when I uninstalled R and reinstalled it (one of the desperate steps I took when I was trying to troubleshoot). Evidently ~My Documents\R\win-library\3.0\whisker survived the uninstallation. Clearly I need to learn more about R installation and the ways in which the libraries can be setup.