hgweb: make viewing of non-text work in hgweb We use mimetypes.guess_type to guess file types and util.binary to determine whether a file is displayable as text. This lets us display displayable text files in our normal source view. Files that appear to be binary will be displayed as something like "(binary:image/gif)". Clicking on raw view will send the raw file with an appropriate MIME type. Thus things like GIFs will now be viewable inside hgweb without making a mess. Further, things like postscript files that are text should show source in the normal view and a browser can launch a postscript viewer for the raw view.