Fixed "Forward Transition" construction of DateTime objects.

This fixes the issue in
https://wiki.php.net/rfc/datetime_and_daylight_saving_time#forward_transitions
There is a period during transition to DST where a time (such as 02:30) does
not exist. PHP already calculated the correct timestamp for this, but failed to
"rounded forward" to the existing correct hour value.
Always reset those parameters.
Fixed forward transitions in diffs.
Group those tests a bit better, as some of the bd ones wanted a "ST" feature that doesn't exist yet.
Split up tests into their different categories.
Fix backwards transition diffs.
Move add/sub to timelib.
Fixed a few DST changeover issues.
Merge branch 'PHP-5.6' of git.php.net:php-src into PHP-5.6

* 'PHP-5.6' of git.php.net:php-src:
  Updated NEWS for Constant Scalar Exprs RFC
  Moved arrays again to "static_scalar:" & little cleanup
  Renaming
  Constant expressions refactoring
  Removed operations on constant arrays. They make no sense as constants are not allowed to be arrays. And as just properties are allowed to; no problem, we still don't need operations on any constant array.
  Added a few more operators
  Whitespace fix
  converted several switches to ifs and made more opcache friendly
  Fatal error about self referencing constants fixed
  Fixed mem leaks, added tests and ternary operator
  Working commit for constant scalar expressions (with constants). Tests will follow.
Marking those two as XFAIL for now.
Merge branch 'date-time-dst-rfc' into PHP-5.4

This is a partial resolve of some DST issues, plenty of things to do, but as
this *does* fix a few issues it's worth merging it already.
Merge branch 'PHP-5.4' into PHP-5.5

Conflicts:
	ext/date/php_date.c
Removed unused "pHashFunction" argument in _zend_hash_init() and family (must be 99% source compatible)
Merge branch 'PHP-5.6'

* PHP-5.6:
  Removed unused "pHashFunction" argument in _zend_hash_init() and family (must be 99% source compatible)
Merge branch 'PHP-5.5' into PHP-5.6
Merge branch 'PHP-5.6'
Merge branch 'master' of git.php.net:php-src