I started writing syntax definitions for Sublime Text — it should do highlighting, code navigation etc.
It's work in progress and I have some ideas about what to add, but not too many. I'll gladly accept suggestions.
Repo: https://gitgud.io/Xellos/qsharp-sublime-syntax.
UPD: It can actually do something now. Currently supports highlighting for, if, operation, namespace syntax (not just keywords, but specific correct syntax) and forbidden keywords.