v0.3.1

• new factory method fromFloatTimestamp()
• throw InvalidTimeStringException in fromString() and fromFormat()

PHP 7.1 release

Merge pull request #5 from pauci/feature/php-7-1

Feature/php 7 1

v0.2.1: Merge pull request #4 from pauci/feature/in-default-timezone

Add new modifier method inDefaultTimezone()