0.0-4 Added is_macos_sierra & fixed other is_osx_* fns.
      Made sys_get_locale more robust across different OSes.
      Added is_visual_studio, is_emacs.
      is_current_package now vectorised (slight breaking change).
      Fixed is_rstudio_desktop and is_rstudio_server.
0.0-3 Added is_r_revised.
      Better handling of bad pkg names in is_package_current.
0.0-2 Added r_can_find_java.
      Fixed is_rstudio_desktop, is_rstudio_server.
      Dropped devtools suggestion.
0.0-1 Content extracted from assertive 0.3-0, and tidied.
