Better support for click in Mermaid diagrams

[Mat Schaffer]

If I add this to a mermaid graph

graph

A[Open Google]
click A "https://google.com" "link test (open in same tab)"

Clicking A opens inside the mermaid diagram frame. 

(before click)

(after click, note error is from google refusing to load in an iframe)

I'd rather it open at the top level (_top), or possibly (_blank) in a new tab.

https://github.com/mermaid-js/mermaid/pull/1585 adds the option to specify a link target.

If you can't add that please at least make _top the default to avoid a very odd picture-in-picture situation with the current "click" behavior.

[Rafael do Nascimento Pereira]

I am impressed, 2,5 years and still no changes.