Create sequence diagrams

[iluwatar]

In addition to class diagrams it would be awesome to support sequence diagrams. After some research, it seems that all of the current presenters support that diagram type, so it should be possible. Here are the examples for each presenter.

Graphviz:

digraph G {
 rankdir="LR";
 node[shape="point"];
 edge[arrowhead="none"]

 {
   rank="same";
   LC[shape="plaintext"]
   LC -> step00 -> step01 -> step02 -> step03 -> step04 -> step05;
 }

 {
   rank="same";
   Agency[shape="plaintext"]
   Agency -> step10 -> step11 -> step12 -> step13 -> step14 -> step15;
 }

 {
   rank="same";
   Agent[shape="plaintext"]
   Agent -> step20 -> step21 -> step22 -> step23 -> step24 -> step25;
 }

 step00 -> step10 [label="sends email new custumer", arrowhead="normal"];
 step11 -> step01 [label="declines", arrowhead="normal"];
 step12 -> step02 [label="accepts", arrowhead="normal"];
 step13 -> step23 [label="forward to", arrowhead="normal"];
 step24 -> step14;
 step14 -> step04 [arrowhead="normal"];
}

PlantUML:

@startuml
Alice -> Bob: Authentication Request
Bob --> Alice: Authentication Response

Alice -> Bob: Another authentication Request
Alice <-- Bob: Another authentication Response
@enduml

Mermaid:

sequenceDiagram
	Alice->>+John: Hello John, how are you?
	Alice->>+John: John, can you hear me?
	John-->>-Alice: Hi Alice, I can hear you!
	John-->>-Alice: I feel great!