RSelenium: get all possible values of a drop down menu

To get all possible values of a drop down menu using RSelenium, leverage the selectTag function after finding the element as described here:

```{r}
webElem <- remDr$findElement(using = 'xpath', "//select[@name='txtTargetToMm']")
opts <- webElem$selectTag()

> opts$text
[1] "JANUARY"   "FEBRUARY"  "MARCH"     "APRIL"     "MAY"       "JUNE"      "JULY"      "AUGUST"   
[9] "SEPTEMBER" "OCTOBER"   "NOVEMBER"  "DECEMBER" 
> opts$value
[1] "1"  "2"  "3"  "4"  "5"  "6"  "7"  "8"  "9"  "10" "11" "12"
> opts$selected
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE
```