- When we change account or community, we cancel all related tasks
- We defined some tasks as being able to run only once
- When a task is started a second time and the firt one is not finished,
the second one is canceled

Replaced every bma_access.get with future_request
All network requests are now done in coroutines except simple_requests

- Beware of python closure parameters in for loops !
- Use the bma_access.get directly in classes that needs
to be refreshed when getting the result, instead