Fix :VimwikiNextTask

Use the correct function for accessing 'rxListItemWithoutCB'.
`ac4d0a1d46` refactored access to vars and it appears this is one place
where `get_syntaxlocal` should have been renamed to `get_wikilocal` but
was accidentally skipped.

autoload/vimwiki/base.vim

@@ -1342,7 +1342,7 @@ endfunction
 
 " Find next task (Exported)
 function! vimwiki#base#find_next_task() abort
-  let taskRegex = vimwiki#vars#get_syntaxlocal('rxListItemWithoutCB')
+  let taskRegex = vimwiki#vars#get_wikilocal('rxListItemWithoutCB')
     \ . '\+\(\[ \]\s\+\)\zs'
   call vimwiki#base#search_word(taskRegex, '')
 endfunction

doc/vimwiki.txt

@@ -3674,6 +3674,7 @@ Contributors and their Github usernames in roughly chronological order:
     - Edward Bassett (@ebassett)
     - Rafael Castillo (@eltrufas)
     - Reiner Herrmann (@reinerh)
+    - Ryan Winograd
 
 
 ==============================================================================
@@ -3692,6 +3693,7 @@ New:~
     * PR #900: conceallevel is now setted locally for vimwiki buffers
     * PR #901: adds multiparagraph blockquotes using email style syntax
     * PR #934: RSS feed generation for diary with :VimwikiRss.
+    * PR #959: Fix :VimwikiNextTask
 
 2.5 (2020-05-26)~
 

test/list_todo.vader

@@ -199,6 +199,23 @@ Expect (4 items toogled):
   * [X] Chap2
   End
 
+################################################################################
+# Todo list with text above
+
+Given vimwiki (TODO list):
+  Some other text
+
+  - [ ] Todo Item
+
+Execute (:VimwikiNextTask):
+  :execute "VimwikiNextTask" | execute 'normal yyp'
+
+Expect (Introduce new todo item):
+  Some other text
+
+  - [ ] Todo Item
+  - [ ] Todo Item
+
 ################################################################################
 # Numbered Todo list