mctq 0.2.0

• Some minor documentation issues were resolved.
• shorter_interval() now don't have the inverse argument. Use longer_interval() instead.
• shorter_duration() and longer_duration(), two functions that return the shorter and the longer duration between two hours, were introduced.
• sjl_sc() and sjl_sc_rel(), two functions that allow the user to compute Jankowski's MCTQ sleep-corrected social jet lag, were introduced.