Do not load whole syntax file for a buffer twice.

Load twice only regexes for a concrete syntax.

autoload/vimwiki/u.vim

@@ -78,3 +78,13 @@ endfunction "}}}
 function! vimwiki#u#escape(string) "{{{
   return escape(a:string, '.*[]\^$')
 endfunction "}}}
+
+" Load concrete Wiki syntax: sets regexes and templates for headers and links
+function vimwiki#u#reload_regexes() "{{{
+  execute 'runtime! syntax/vimwiki_'.VimwikiGet('syntax').'.vim'
+endfunction "}}}
+
+" Load syntax-specific functionality
+function vimwiki#u#reload_regexes_custom() "{{{
+  execute 'runtime! syntax/vimwiki_'.VimwikiGet('syntax').'_custom.vim'
+endfunction "}}}