I needed to create some Fields and Templates via API and it was always a pain to get the right settings (like columwith, field context settings and so on). With the brand new (and ALPHA) RockSVN Module you can create your fields via the backend and then show a diff of your changes. Please see the comments on top of the module for todos and limitations.  I'm not totally happy with the diff tool, so if anybody knows a better one or knows ho to change the behaviour to line-based diff (tha