Global Options Chunk for Knitr in RMarkdown Documents

knitr_header.r

### 
### Thanks to Karl Broman http://kbroman.org/knitr_knutshell/pages/Rmarkdown.html

```{r global_options, include=FALSE}
rm(list=ls()) ### To clear namespace
library(knitr)
opts_chunk$set(fig.width=12, fig.height=8, fig.path='Figs/',
               echo=TRUE, warning=FALSE, message=FALSE)
```