ENH: Review data collection pre-session

[helenelajous]

Adds more specific details about the settings before starting the scanning session

[helenelajous]

Lines 80 to 182 refer to the setting of the ET: I think there should be a dedicated section (now, "INSIDE the scanner room" and "Back OUTSIDE THE SCANNER ROOM (control room)" are at the same level as "Setting up the eye-tracker").

[oesteban]

LGTM (added suggestions to make the code more readable and the instructions hopefully more clear - no red mushroom buttons involved this time)

[helenelajous]

Minor comments:

• I would remove mention of button 3
• line 26: would it be possible to have the icon of a locker in open lock position instead?
• I would include the current sections "INSIDE the scanner room" and "Back OUTSIDE THE SCANNER ROOM (control room)" as subsections of the section "Setting up the eye-tracker"

Looks great!