What is the best way to modify or remove default snippets or completions?
Adding the canvas element to HTML can be done easily by adding it to Packages\User\HTML\HTML.sublime-completions.
However, what if I want to get rid of the frameset element defined in Packages\HTML\HTML.sublime-completions? Or if I want to change the html snippet defined in Packages\HTML\html.sublime-snippet to include a <!DOCTYPE html>?
If I copy html.sublime-snippet over to Packages\User\HTML and edit it there, both will exist, instead of the one in Packages\HTML being overridden. And HTML.sublime-completions from both Packages\HTML and Packages\User\HTML are in use, so even if frameset isn't defined in Packages\HTML\HTML.sublime-completions it still exists.
Should I just edit the files directly in Packages\HTML? That doesn't seem very clean, and won't they get recreated on upgrade?