Log message:
Initial import of stringr v0.6.2 as textproc/R-stringr.

stringr is a set of simple wrappers that make R's string functions
more consistent, simpler and easier to use.  It does this by ensuring
that: function and argument names (and positions) are consistent, all
functions deal with NA's and zero length character appropriately, and
the output data structures from each function matches the input data
structures of other functions.

Note: this commit is part of reorganizing some of the recently
imported R packages, which are being reimported into more appropriate
categories (and removed from math) as a result of a recent discussion
on tech-pkg and privately with wiz@.  See the thread starting with:

  http://mail-index.netbsd.org/tech-pkg/2014/09/05/msg013558.html