Too many clicks to add a tag to a blog post

[pascalc]

Adding tags to a block post is not very convenient, you have to: 1/ click on "choose from the list" link to show available tags 2/ click on the tags you want to add 3/ click on "OK" to validate them 4/ click on "save blog post"

That's 4 clicks to add a tag to an existing blog post. I think that tagging a blog post is a very common practice and it should be done in a one click operation, two at most. The tag list should always be displayed by default and clicking on a tag should add the tag to the blog post via an xmlhttprequest, the form field should be used only to add new tags to the list.

[xave]

See #381