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

- Crash if no window fork could be found
- AWAITING and VALIDATING transaction could not be checked again
if the fork size did reduce too much and they were too far from it

- 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