v4.0.0 RC1

This release use patched core library.
Core library was migrated to PHP 7.1 with forced types and it is no longer only namespaced official library. It could be BC break. But changes in official library will be ported into that core library.
Core library was also migrated from DateTime to DateTimeImmutable, it is also BC break.

Library returns (and requires):

• TRUE/FALSE from bool property which in previous version returns '1'/'0'.
• float number instead of (string)number_format($number, 2, '.', '')
• int number instead of (string)$number
• DateTimeImmutable instead of DateTime