title: R rmarkdown hyphen/dash in table turns to dot in output
body: <p>Lets say I have the following table (dataset) and knit it in a rmarkdown document:</p>
  
  <pre><code>```{r global_options, include=FALSE, eval=TRUE, results='asis'}   
  knitr::opts_chunk$set(echo=FALSE, #this sets up chunks, can then edit ones we want individually
                    warning=FALSE, 
                    message=FALSE,
                   eval=FALSE)
  library(kableExtra)
  ```
  
  ```{r , eval=TRUE, results='asis'}
  test &lt;- structure(list(`Dependent: Surv(time, status)` = c("Age", "", 
      ""), c("&lt;40 years", "40-59 years", "60+ years"), `HR (univariable)` = c("-", 
      "0.76 (0.53-1.09, p=0.132)", "0.93 (0.66-1.31, p=0.668)"), `HR (multivariable)` = c("-", 
      "0.79 (0.55-1.13, p=0.196)", "0.98 (0.69-1.40, p=0.926)")), .Names = c("Dependent: Surv(time, status)", 
      "", "HR (univariable)", "HR (multivariable)"), row.names = c(NA, 
      3L), class = "data.frame")
  knitr::kable(test, row.names=FALSE)
  ```
  </code></pre>
  
  <p>The hyphens turn to dots and I am wondering why this is:</p>
  
  <p><a href="https://i.stack.imgur.com/1Hjot.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1Hjot.png" alt="enter image description here"></a>
  EDIT: I have since found out it seems to be when I load <code>library(kableExtra)</code>, if I remove this it works. I have also found this related question <a href="https://github.com/haozhu233/kableExtra/issues/223" rel="nofollow noreferrer">https://github.com/haozhu233/kableExtra/issues/223</a> </p>
  
  <p>As per helpful suggestion below, <code>test[test== "-" ] &lt;- "--"</code> is a work around.</p>
  
  <pre><code>R&gt;sessionInfo()
  R version 3.3.1 (2016-06-21)
  Platform: x86_64-w64-mingw32/x64 (64-bit)
  Running under: Windows 7 x64 (build 7601) Service Pack 1
  
  locale:
  [1] LC_COLLATE=English_Ireland.1252  LC_CTYPE=English_Ireland.1252    LC_MONETARY=English_Ireland.1252
  [4] LC_NUMERIC=C                     LC_TIME=English_Ireland.1252    
  
  attached base packages:
  [1] stats     graphics  grDevices utils     datasets  methods   base     
  
  loaded via a namespace (and not attached):
   [1] backports_1.1.0 magrittr_1.5    rprojroot_1.2   htmltools_0.3.6 tools_3.3.1     yaml_2.1.14     Rcpp_0.12.16   
   [8] stringi_1.2.3   rmarkdown_1.10  knitr_1.20      stringr_1.3.1   digest_0.6.15   evaluate_0.10.1
  </code></pre>