title: npm non-destructive update
body: <p>I'm making a node.js project in Typescript and some of the packages don't have the built-in *.d.ts declaration files, so I went to DefinitelyTyped and got the files and added them to the node packages. The issue is, that when I do an npm update, the files get removed: is there a way for I can update my node packages without it removing these "unmanaged"  files?</p>