v1.4.0

Biggest release so far!

• Introducing MO files support! Thanks to @Dexus for the implementation.
• We have changed the way to parse the plural expressions by implementing our own plural expression parser. Thanks to @Dexus again for the hard work on this! Now this package has no external dependencies, which was a goal to achieve.
• New Translator interface allows Locale objects to use any translation source backend (non-gettext).
• Locale and Po objects now can be serialized. They implement the encoding.BinaryMarshaler and encoding.BinaryUnmarshaler interfaces. This way they can be cached as []byte to avoid translation file parsing in concurrent environments.
• Added support for Go Modules. Now a project using Go Modules can import this package as a module outside the GOPATH.

Relevant commits:

• a19c5fd
• cd46239
• 8e9d9df
• 4cbf30d
• f28243c