~singpolyma/dhall-haxe

Add build/ report/ to gitignore
Rename php to php7 specifically
Use debian stable for python build

But update to newer Haxe, because we need it.  Needed because this
version of Haxe still generates Python that 3.7 cannot run (because of
new await keyword).
Switch to haxelib install all but grab moon-peg from my fork
Add hamcrest and haxe-files to build
Install munit before build

Since we use it to run the tests
Configure haxelib before build