TinyMceSettings.AddPlugin should take list of plugins as argument

Description

As a developer, I would like to add plugins to the default setting.

Before this big fix was released, if I added extra plugins, it looked like this.

config.Default()
    .AddPlugin("table")
    .AddPlugin("paste")
    .AddPlugin("spellchecker")
    .AddPlugin("searchreplace")

With this bug fix, I can use this shortened syntax.

config.Default()
    .AddPlugin("table", "paste", "spellchecker", "searchreplace")