I started building a basic axoloti syntax highlighting package for visual studio code. So far it handles .axo and .axp files fairly well. It will interpret the files as xml and all cdata blocks are highlighted as c code. Nothing fancy beyond that, however.
I put it up on github if anyone is interested: https://github.com/20after4/axoloti-vscode
The package should be easily portable to Atom editor since vs.code is based on atom. Additionally, the .tmLanguage file should be usable in either Sublime Text or Textmate, for those of you who aren't using visual studio code.