Kill computation
This merge request :
- adds the possibility to abord a computation, including the choice of removing computation's directory or not (removing directory is not working when using socket monitoring tool)
- includes button and checkbox in Notebook 'compute Widget' according to that feature
- removes all functions and features from main computation script (formerly 'encapsulate.py') and includes them in Worker object, which becomes more than just a communication tools
- renames the script 'encapsulate.py' to 'swaf_compute.py'
- improves the messaging system by naming RegEx groups for a better readability