A bit of a faff, but working.

Apart from some minor issues, this is a basic, working plugin.

Some downsides:
– If you add a testimonial, too many fields are required. I do not need a project name, a url, a country and tags. For me, Customer name, City and Description suffice. In fact, only description should be required, because that is the only essential part of a testimonial. Having all of these required fields is annoying, because it takes so much more time to enter a testimonial.

– In the list I see a backslash before an apostrof, which is an indication that addslashes is used when saving to the database or no proper removal of slashes is done prior to displaying the value to the user. There is some weirdness in WordPress regarding this that I can’t remember, but it can and should be solved.