vim-patch:8.1.2019: 'cursorline' always highlights the whole line (#15161)

Problem:    'cursorline' always highlights the whole line.
Solution:   Add 'cursorlineopt' to specify what is highlighted.
            (closes vim/vim#4693)
410e98a70b

src/nvim/options.lua

@@ -555,6 +555,13 @@ return {
       redraw={'current_window_only'},
       defaults={if_true={vi=false}}
     },
+    {
+      full_name='cursorlineopt', abbreviation='culopt',
+      short_desc=N_("settings for 'cursorline'"),
+      type='string', scope={'window'},
+      redraw={'current_window_only'},
+      defaults={if_true={vi="both"}}
+    },
     {
       full_name='debug',
       short_desc=N_("to \"msg\" to see all error messages"),