Updated!
AAAPackageDev helps create and edit snippets, completions files, build systems and other Sublime Text extensions.
The general workflow looks like this:
1. run new_* command (new_raw_snippet, new_completions, new_syntax_def...)
2. edit file (with specific snippets, completions, higlighting, build systems...)
3. save file
AAAPackageDev new_* commands are typically accessible through the Command Palette (Ctrl+Shift+P).
The latest version is available here:
https://github.com/SublimeText/AAAPackageDev