update doc for data selection and hdf5 scan concatenation

context

Update of the documentation after edf and hdf5 data selection (!352 (merged)) and adding scan concatenation (!335 (merged) )

details

• convert user guide from pdf to html (close #139 (closed))
• upgrade user guide to use hdf5 by default instead of edf
• upgrade some widget documentation
• add 'sphinxcontrib-video' to the dependencies (allows to display the 'demo' video directly)