Merge example and demo project

[daadu]

Pros:

• commands like flutter pub get work properly
• lesser management/boiler code
• single integration and build test - with CI

[daadu]

@WieFel Let me know your views on it.

[WieFel]

@daadu actually a good idea ;) so you mean to have something like a subfolder inside example/lib which contains the demo code?

[daadu]

yes something like

example/
  - lib/
    - demo/
    - main.dart # entry-point (default) for running "example"
    - main_demo.dart  # entry-point for running "demo"

[WieFel]

@daadu yes just go ahead with this ;)

[daadu]

Will do this when we start working on test - integration test in particular.