Yes… that helped a lot… and now everything works fine! The problem was caused by a “crash-recovered” folder with wordpress installation. Some permissions were left as per previous installation…
Well, sorry for everything.
I’ve got the plugin to work and the .svg to show up.
As my previous comment, I had to add these two lines on .htaccess to tell Apache to serve .svg files as <image/svg+xml> and not as <text/plain>:
AddType image/svg+xml svg
AddType image/svg+xml svgz
UPDATE
Browsers end up retrieving not a mime type <image/svg+xml> but a <text/plain> mime type. I think this depends on the web server configuration.
Here a link clarifying how to set up server to serve <image/svg+xml> for .svg files http://www.w3.org/services/svg-server/? but unfortunately I cannot check if this works until monday (do not have full access from home).
Hope this can work.