Merge branch 'release/2.6.5'

Merge tag '2.6.4' into develop

v2.6.4

v2.6.3

release 2.6.2

Release 2.6.0

pre-release 2.6.0-rc1

add build status for develop branch

Restore compatibility with PHP 5.4

Merge branch 'release/2.5.0'