fixes #4989

Enhances `normalizeDateTimeValue` to return a DateTime object instead of a converted double value, that fails. The DateTime object input is supported by 32 bit, 64 bit, as well as the `IntlDateFormatter` to format all years. (including fixing of the Y2K38 bug). Fixes issue in #4989.

close #5000

use "just now" for empty time difference in Formatter.

fixed wrong language name definition

adding and reworking the conversion of:
- ICU to PHP
- PHP to ICU
- ICU to JUI
- PHP to JUI

This fix ensures the format configured in the formatter class is used in the message instead
of the default ICU format.

fixes #4960

ensure some features that were recently added to formatter keep working after refactoring

neads cleanup

- removed unformat methods, they do not belong here
- removed db format, which is also not purpose of this class
- refactored the whole set of methods to be simpler and better
  maintainable

More unit tests needed.

#2359 one test failed in Travis because standard medium date format is different in Travis then on my locale PC.

Refactored formatter class #2359 which works with or without intl extension. Use PHP format patterns alsow with intl. Class is compatible with previous version.

Convert string values to floating point, so that `number_format` method can properly format values.

Adds support for timestamps beyond year 2038.

Adjustments code according to the standards.
Adding missing PHPDoc comment.

Fixed phpdoc, removed unit tests for Formatter asRelativeTime that were relative to current time since it was impossible to specify correct expected values