Improvements to next_view and add prev_view, goto_view

[CRAG666]

Add the functions described some time ago in an ISSUE #161 , also through Isort format its imports a bit, in order to make them more legible. The specific functions are as follows:

• move_next_view: an improvement of the original written
  • move_Prev_view: It is exactly the same as next_view but reverse
  • goto_view: focus especific view by index