Add a new wrapping mode to the TextEditor that will wrap lines at the
spaces between words.
Replace the previous menubar checkbox 'Wrapping Mode' in HackStudio and
the TextEditor with an exclusive submenu which allows switching between
'No wrapping', 'Wrap anywhere' and 'Wrap at words'. 'Wrap anywhere' (the
new 'Wrap lines') is still the default mode.
Setting the wrapping mode in the constructors of the TextEditorWidget
and HackStudio has been removed, it is now set when constructing the
menubar actions.
Code meant for the move_to_next_word functions which set the cursor to
the last character in the file if it was reached was copied into the
move_to_previous_word functions which lead them not moving when
the function was called from the end of the file.
Implemented move_to_beginning_of_next(), move_to_end_of_next(),
move_to_beginning_of_previous() and move_to_end_of_previous() functions
for more correct word jumping than the move_to_xxx_span() methods that
were previously used.