Minor refactoring of the data, movement and video modules
Creating utils/beacons.py to manage analysis of interaction with the beacons
Changing raw_pos/METADATA.json. Starting point of block 1.

From timestamp 9 to 100. To remove the start of the block where
the beacons are still not on the dance floor.
Adding a ploting utility for nice bars per group per block
Preliminary notebook analysis of participants near beacons