v4.0.0

This is a major update. Please read docs before updating from v3.2 to v4.0.

• PHP 7.1 or later is required.
• Renamed class from TranslateClient to simply GoogleTranslate.
• Removed array translation which was not working (might add later).
• Changed signatures of methods (see docs).
• Separate static trans() and non-static translate() methods.
• Updated dependencies.
• Various bugfixes.