Allow customization of header level of TOC

Instead of forcing the TOC to always be at header level 1, allow the
user to specify via the option g:vimwiki_toc_header_level what level
they want.

This defaults to 1, so if the user does nothing then the old behavior
will remain the same.

autoload/vimwiki/base.vim

@@ -358,7 +358,7 @@ function! vimwiki#base#generate_links()
 
   let links_rx = '\m^\s*'.vimwiki#u#escape(vimwiki#lst#default_symbol()).' '
 
-  call vimwiki#base#update_listing_in_buffer(lines, 'Generated Links', links_rx, line('$')+1, 1)
+  call vimwiki#base#update_listing_in_buffer(lines, 'Generated Links', links_rx, line('$')+1, 1, 1)
 endfunction
 
 
@@ -1015,14 +1015,14 @@ endfunction
 
 " creates or updates auto-generated listings in a wiki file, like TOC, diary
 " links, tags list etc.
-" - the listing consists of a level 1 header and a list of strings as content
+" - the listing consists of a header and a list of strings as content
 " - a:content_regex is used to determine how long a potentially existing list is
 " - a:default_lnum is the line number where the new listing should be placed if
 "   it's not already present
 " - if a:create is true, it will be created if it doesn't exist, otherwise it
 "   will only be updated if it already exists
 function! vimwiki#base#update_listing_in_buffer(strings, start_header,
-      \ content_regex, default_lnum, create)
+      \ content_regex, default_lnum, header_level, create)
   " Vim behaves strangely when files change while in diff mode
   if &diff || &readonly
     return
@@ -1031,7 +1031,8 @@ function! vimwiki#base#update_listing_in_buffer(strings, start_header,
   " check if the listing is already there
   let already_there = 0
 
-  let header_rx = '\m^\s*'.substitute(vimwiki#vars#get_syntaxlocal('rxH1_Template'),
+  let header_level = 'rxH' . a:header_level . '_Template'
+  let header_rx = '\m^\s*'.substitute(vimwiki#vars#get_syntaxlocal(header_level),
         \ '__Header__', a:start_header, '') .'\s*$'
 
   let start_lnum = 1
@@ -1083,7 +1084,7 @@ function! vimwiki#base#update_listing_in_buffer(strings, start_header,
 
   " write new listing
   let new_header = whitespaces_in_first_line
-        \ . s:safesubstitute(vimwiki#vars#get_syntaxlocal('rxH1_Template'),
+        \ . s:safesubstitute(vimwiki#vars#get_syntaxlocal(header_level),
         \ '__Header__', a:start_header, '')
   keepjumps call append(start_lnum - 1, new_header)
   let start_lnum += 1
@@ -1875,7 +1876,13 @@ function! vimwiki#base#table_of_contents(create)
 
   let links_rx = '\m^\s*'.vimwiki#u#escape(vimwiki#lst#default_symbol()).' '
 
-  call vimwiki#base#update_listing_in_buffer(lines, toc_header_text, links_rx, 1, a:create)
+  call vimwiki#base#update_listing_in_buffer(
+        \ lines,
+        \ toc_header_text,
+        \ links_rx,
+        \ 1,
+        \ vimwiki#vars#get_global('toc_header_level'),
+        \ a:create)
 endfunction
 
 

autoload/vimwiki/diary.vim

@@ -287,7 +287,7 @@ function! vimwiki#diary#generate_diary_section()
   if vimwiki#path#is_equal(current_file, diary_file)
     let content_rx = '^\%(\s*\* \)\|\%(^\s*$\)\|\%('.vimwiki#vars#get_syntaxlocal('rxHeader').'\)'
     call vimwiki#base#update_listing_in_buffer(s:format_diary(),
-          \ vimwiki#vars#get_wikilocal('diary_header'), content_rx, line('$')+1, 1)
+          \ vimwiki#vars#get_wikilocal('diary_header'), content_rx, line('$')+1, 1, 1)
   else
     echomsg 'Vimwiki Error: You can generate diary links only in a diary index page!'
   endif

autoload/vimwiki/html.vim

@@ -1078,7 +1078,7 @@ function! s:process_tag_h(line, id)
 
     else
 
-      let h_part = '<div id="'.h_id.'" class="toc"><h1 id="'.h_id.'"'
+      let h_part = '<div id="'.h_id.'" class="toc"><h'.h_level.' id="'.h_id.'"'
 
     endif
 

autoload/vimwiki/tags.vim

@@ -329,7 +329,7 @@ function! vimwiki#tags#generate_tags(...) abort
         \ .vimwiki#u#escape(vimwiki#lst#default_symbol()).' '
         \ .vimwiki#vars#get_syntaxlocal('rxWikiLink').'$\)'
 
-  call vimwiki#base#update_listing_in_buffer(lines, 'Generated Tags', links_rx, line('$')+1, 1)
+  call vimwiki#base#update_listing_in_buffer(lines, 'Generated Tags', links_rx, line('$')+1, 1, 1)
 endfunction
 
 

autoload/vimwiki/vars.vim

@@ -171,6 +171,7 @@ function! s:read_global_settings_from_user()
         \ 'table_auto_fmt': {'type': type(0), 'default': 1, 'min': 0, 'max': 1},
         \ 'table_mappings': {'type': type(0), 'default': 1, 'min': 0, 'max': 1},
         \ 'toc_header': {'type': type(''), 'default': 'Contents', 'min_length': 1},
+        \ 'toc_header_level': {'type': type(0), 'default': 1, 'min': 1, 'max': 6},
         \ 'url_maxsave': {'type': type(0), 'default': 15, 'min': 0},
         \ 'use_calendar': {'type': type(0), 'default': 1, 'min': 0, 'max': 1},
         \ 'use_mouse': {'type': type(0), 'default': 0, 'min': 0, 'max': 1},

doc/vimwiki.txt

@@ -2872,6 +2872,15 @@ appropriate word in your mother tongue like this: >
 The default is 'Contents'.
 
 
+------------------------------------------------------------------------------
+*g:vimwiki_toc_header_level*
+
+The header level of the Table of Contents (see |vimwiki-toc|). Valid values
+are from 1 to 6.
+
+The default is 1.
+
+
 ------------------------------------------------------------------------------
 *g:vimwiki_map_prefix*