0.2.0

Added

• Feature to read string to encode from standard input, which allows to pipe
  commands to qr-rs (closing issue #1).
• border CLI option to specify border size.
• error-correction-level CLI option to specify QR error-correction-level as
  one of the following values:
  • low;
  • medium;
  • quartile;
  • high.

0.1.0

Initial release.