Remove trailing and leading blanks for oins and pins

[MansMeg]

Now leading and trailing blanks are not removed. See:

# returns string w/o leading whitespace
trim.leading <- function (x)  sub("^\\s+", "", x)

# returns string w/o trailing whitespace
trim.trailing <- function (x) sub("\\s+$", "", x)

# returns string w/o leading or trailing whitespace
trim <- function (x) gsub("^\\s+|\\s+$", "", x)

[eribul]

There is also a function base::trimws already available in R :-)

[MansMeg]

That's great!
Maybe we should try to remove the stringr package from dependencies in the long run. And maybe even move lubridate to suggested (and import when used).