Update PHPDoc: missing throws InvalidArgumentException

Don't override the timezone when called with a DateTime object

Use Locale::getDefault() before setlocale(LC_TIME, '0') for get defau…

…lt locale

Minus prefix should also remove leading space (#13)

* Minus prefix should also remove space

Standard PHP strftime() also remove leading space when using the minus prefix.

* Add asserts for test '%#e' and '%-e'

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Co-authored-by: Fernando Herrero <[email protected]>

"Stand-alone" versions of "month in year" and "day of week" formats m…

…ore closely mimic strftime in German locale #12

Test: use assertThat instead assertMatchesRegularExpression

Fix fatal error when using the default PHP locale #17

Message in new tests, php version to 7.1

Fixed %k example