Update Haxe.xml

Related to:
https://github.com/fdorg/flashdevelop/pull/95

The "macro" keyword was forgotten to be added to  the list.
I also put "abstract" in front in order to restore the alphabetic order.
Merge pull request #276 from dagnelies/patch-1

macro keyword was forgotten in older pull request
Merge branch 'master' into plugins