Allow any visual mode to be used to create a link

The only real condition we care about is whether the selection is
contained within a single line.  It is practical to do something like
V<CR> to link a whole line, and AFAIK there is no reason for why that
doesn't work.

autoload/vimwiki/base.vim

@@ -1986,7 +1986,7 @@ function! s:normalize_link_syntax_v()
     endif
 
     " Put substitution in register " and change text
-    call setreg('"', sub, 'v')
+    call setreg('"', substitute(sub, '\n', '', ''), visualmode())
     normal! `>""pgvd
   finally
     call setreg('"', default_register_save, registertype_save)
@@ -2002,8 +2002,8 @@ function! vimwiki#base#normalize_link(is_visual_mode)
   else
     if !a:is_visual_mode
       call s:normalize_link_syntax_n()
-    elseif visualmode() ==# 'v' && line("'<") == line("'>")
-      " action undefined for 'line-wise' or 'multi-line' visual mode selections
+    elseif line("'<") == line("'>")
+      " action undefined for multi-line visual mode selections
       call s:normalize_link_syntax_v()
     endif
   endif

autoload/vimwiki/markdown_base.vim

@@ -122,7 +122,7 @@ function! s:normalize_link_syntax_v()
           \ '__LinkUrl__', visual_selection, '')
     let link = s:safesubstitute(link, '__LinkDescription__', visual_selection, '')
 
-    call setreg('"', link, 'v')
+    call setreg('"', substitute(link, '\n', '', ''), visualmode())
 
     " paste result
     norm! `>""pgvd
@@ -141,8 +141,8 @@ function! vimwiki#markdown_base#normalize_link(is_visual_mode)
   else
     if !a:is_visual_mode
       call s:normalize_link_syntax_n()
-    elseif visualmode() ==# 'v' && line("'<") == line("'>")
-      " action undefined for 'line-wise' or 'multi-line' visual mode selections
+    elseif line("'<") == line("'>")
+      " action undefined for multi-line visual mode selections
       call s:normalize_link_syntax_v()
     endif
   endif