Links to callbacks

A has a tooltip and a callback
B has a link and a tooltip
C has a long tooltip
graph LR; A-->B; B-->C; click A callback "Tooltip" click B "http://www.github.com" "This is a link" click C callback "Tooltip quite long tooltip. So long that several rows are required... Not just two rows..."

Links to urls

A second diagram that should have its own callback on A even though the node has the same id.
graph LR; A-->B B-->C click A callback2 "Tooltip3"

Issue #272

graph LR; A((start))-->B(step1); B-->C[step2]; C-->D{step3}; D-->E[end]; classDef green fill:#9f6,stroke:#333,stroke-width:1px; class A,B,C,D,E green; click B onNodeClick "tooltip"