architecture documentation

[mleu]

Extend sad.md with

• [ ] dataflow-diagramm
• [ ] table of used technologies
• [ ] picture showing assembly line, similar to https://forum.ionicframework.com/t/is-there-a-graphic-diagram-available-that-shows-how-ionic-2-and-all-related-technologies-connect/88375/16
• [ ] component diagram with links based on imports
• [ ] design principles, answering for example
  • when does it belong on a page, when in a service?
  • why did we choose Rx/Observables programming?
  • why Dependency Injection?
  • what is a Model?
  • why are some things not needed: Interfaces,
• [ ] get feedback from advisor if on right path
• [ ] redraw existing diagrams in new tool

[mleu]

Split into #481 #482 #483 #484 #485 #486