New strtotime implementation (#373)
New strtotime implementation (#373)

* New strtotime implementation

THIS IS A BREAKING CHANGE, some old behavior, which relied on JS-engine built-in date parsing, is removed.
This patch re-implements strtotime based on PHP's source code. It is not 100% complete.
Missing are:
- weekdayof
- this time-unit, eg. this week
- time zone handling (e.g. Europe/Berlin, GMT, Z)

* Use es6 syntax for method definition

kvz/phpjs,kvz/phpjs,kvz/phpjs,kvz/phpjs