luajr 0.1.7

• Added support for passing the R type "raw" to Lua, as a string potentially
  with embedded nulls, and for returning strings with embedded nulls from
  Lua, which become "raw"s in R.

• Replaced calls to Rf_allocVector3 with calls to Rf_allocVector, as the
  former is apparently not part of the API allowed in CRAN packages, as
  requested by CRAN.

• @TimTaylor improved the R version of the "logistic map" example and
  benchmark in the main luajr vignette, so that now the R version is only
  10x slower than the Lua version, not 2,500x slower. This fixes issue
  #2. Thanks Tim!

• Removed a compiler flag, -Wformat, that was causing errors with some
  standard R environments, most notably the rocker/r-base Docker
  environment. This fixes issue
  #1. Thanks @jonocarroll
  for reporting and helping to fix luajr's first official bug! :-)