title: compiling minimal knitr example fails
body: <p>I'm working on getting knitr setup. I installed the latest version of R (2.15.1), Lyx 2.0 including the MiKTex 2.9 distribution, and RStudio 0.96.304 on a Windows 7 Enterprise box. I can get pdflatex output if I open up Lyx and simply view the tutorial, so the basic system is working. I then downloaded the <a href="https://github.com/yihui/knitr/blob/master/inst/examples/knitr-minimal.Rnw">minimal Rnw example</a> saved it in my working directory as testknitr.Snw, opened that file in RStudio, and pressed the compile PDF button. The knitr output completes with a single warning about the parser package, and produces a file testknitr.tex. pdflatex.exe then runs, but fails, and the particular error in the log file seems to be  </p>
  
  <pre><code> ! LaTeX Error: Environment alltt undefined.  
  </code></pre>
  
  <p>I received the same error when attempting to compile testknitr.tex using TexWorks. I created that file from inside R using knit("testknitr.Rnw") - different extension because of the default in RStudio. I did tell MikTek to update packages automatically when compiling. A bit of research on <a href="http://www.ctan.org/pkg/alltt">CTAN</a> suggests that the alltt environment is part of the ltxbase package, which is installed when I look at the package manager. In fact it seems like a pretty core part of the whole thing!</p>
  
  <p>OK - I was reading the comments on the minimal example page, and discovered a workaround to that problem, and that it is a known bug as of 19 hours ago. And yes, I doublechecked that RStudio is set to use knitr, not sweave. I now get a new error:</p>
  
  <pre><code>! LaTeX Error: Command \textquotesingle unavailable in encoding T1. 
  </code></pre>
  
  <p><strong>EDIT:</strong> OK! it turns out that error isn't fatal - there's a lovely pdf of the minimal example sitting in the working directory if one takes the time to look. Somewhat alarming that RStudio thinks compilation failed when it didn't? </p>