Production ready

Merge branch 'master' of https://github.com/emilkm/amfext

Move master to php72

v.0.0.0.21

Add tests for bytearray no string reference.

v.0.0.0.20

#3 Fix writing byte array greater than 128 bytes

v.0.0.0.19

Fix read _explicitClass from namespace.

v0.0.0.18

Update version and config.m4

v0.016

Working without userland callbacks. Date and ByteArray done. Vector, Xml, XmlDocument todo.