Taxonomy error messages show success colors

[ninnypants]

When attempting to update a taxonomy fails the message is shown with a green update border instead of the red error border.

Steps to reproduce:

1. Create two tags
2. Edit the second tag
3. Attempt to change the slug of the second tag to be the same as the first

After hitting update you will be take to the list of all tags and the message "Tag not updated." Will show with a green border.

[mzak]

Added conditional to check what message is returned, and set the class accordingly

[ninnypants]

Replying to mzak:

31241.diff wont cover all other error instances. Maybe try using keys from the $messages array further up in that file.

[mzak]

Use the message key, rather than the error string to determine which class to output

[ninnypants]

I have the patch 31241.2.diff working in trunk locally

[mzak]

Updated to comply with coding standards

[helen]

The messages can be filtered, and there are four different notice types (success, warning, error, info) - what could we do to support custom messages and varying notice types? That is probably a bigger picture thing, and applies to messages in other places, but I want us to be thinking about that.

[rahulbhangale]

Filtering of messages can be done by sending the message type with url parameter.

[SergeyBiryukov]

Some cleanup in 31241.5.diff​.

[ocean90]

In 31823:

Edit Terms: Show error messages actually as error messages.

props rahulbhangale, SergeyBiryukov.
fixes #31241.