v0.3.1

Thanks to Camilo, Glenn Jackman, and Bruce Axtens for their contributions!

• (enh) ctrl-H / backspace handling (#19)
• (enh) add Process.chdir
• (fix) use absolute paths for module directory resolution
• (enh) add Runtime.assertVersion
• (env) add Ensure module for argument validation (#13)
  • Ensure.string(_,_), Ensure.num(_,_), etc.
• (fix) Path normalize ./../ works corretly now (#14)
• (enh) File.dirname and File.basename (#16)
• (enh) add Runtime.hasCapability - better capability detection via
• (enh) Improvements from newer wren-essentials
  • add json module for JSON encode/decode
  • additional Strings utility functions
  • upcase/downcase now support Unicode strings
• Also includes minor fix that prevented v0.3.0 from working properly.