Add shape: v0.3.0

[taillades]

Add shape as a distinct category. Compatible with former data.json format.

The commits consists in:

• copycats of dms functions into shape function
• adaptations of dms functions into signal function, with an argument to make it dms or shape
• removal of a few inconsistencies found when parsing the code
• import dataset generates numpy arrays everytime by default since it doesn't take time
• numpy arrays are being saved with a decorator now. Not a new feature, just elegance
• import dataset doesn't take a data argument anymore. Dataloader takes one in DMSensei though
• some useless features for summing two list of datapoints

The commit passes the tests locally - we need to fix the testing pipeline of Github actions!