Add option to set a character which replaces spaces when creating links.

The wikilocal option links_space_char will be used to replace any spaces
when creating a new wiki link and page. This only affects link creation
with a visual selection.

autoload/vimwiki/base.vim

@@ -2134,7 +2134,8 @@ function! s:normalize_link_syntax_v()
     endif
 
     " Put substitution in register " and change text
-    call setreg('"', substitute(sub, '\n', '', ''), visualmode())
+    let sc = vimwiki#vars#get_wikilocal('links_space_char')
+    call setreg('"', substitute(substitute(sub, '\n', '', ''), '\s', sc, 'g'), visualmode())
     normal! `>""pgvd
   finally
     call setreg('"', default_register_save, registertype_save)

autoload/vimwiki/markdown_base.vim

@@ -122,7 +122,8 @@ function! s:normalize_link_syntax_v()
           \ '__LinkUrl__', visual_selection, '')
     let link = s:safesubstitute(link, '__LinkDescription__', visual_selection, '')
 
-    call setreg('"', substitute(link, '\n', '', ''), visualmode())
+    let sc = vimwiki#vars#get_wikilocal('links_space_char')
+    call setreg('"', substitute(substitute(link, '\n', '', ''), '\s', sc, 'g'), visualmode())
 
     " paste result
     norm! `>""pgvd

autoload/vimwiki/vars.vim

@@ -269,6 +269,7 @@ function! s:populate_wikilocal_options()
         \ 'exclude_files': {'type': type([]), 'default': []},
         \ 'ext': {'type': type(''), 'default': '.wiki', 'min_length': 1},
         \ 'index': {'type': type(''), 'default': 'index', 'min_length': 1},
+        \ 'links_space_char': {'type': type(''), 'default': ' ', 'min_length': 1},
         \ 'list_margin': {'type': type(0), 'default': -1, 'min': -1},
         \ 'maxhi': {'type': type(0), 'default': 0, 'min': 0, 'max': 1},
         \ 'nested_syntaxes': {'type': type({}), 'default': {}},

doc/vimwiki.txt

@@ -2055,6 +2055,21 @@ converted to HTML at the moment.
 To use Markdown's wiki markup: >
   let g:vimwiki_list = [{'path': '~/my_site/',
                        \ 'syntax': 'markdown', 'ext': '.md'}]
+
+*vimwiki-option-links_space_char*
+------------------------------------------------------------------------------
+Key                 Default value~
+links_space_char    ' '
+
+Description~
+Set the character (or string) used to replace spaces when creating a link. For
+example, setting '_' would transform the string 'my link' into [[my_link]] and
+the created file would be my_link.wiki. The default behavior does not replace
+spaces.
+
+To set the space replacement character: >
+  let g:vimwiki_list = [{'path': '~/my_site/',
+                       \ 'links_space_char': '_'}]
 <
 
 *vimwiki-option-template_path*