Fixed an issue with duplicate lines shown in the editor.

This can happen when the line is too long for one line and can wrap; if it
also includes hidden markup (Markdown in comments), this markup can change
the length of the line, but it's not adjusted by Scintilla after the
markup is applied. Force adjustment when this situation is detected.

src/editor/markup.lua

@@ -143,6 +143,7 @@ function MarkupStyle(editor, lines, linee)
   end
 
   local es = editor:GetEndStyled()
+  local needfix = false
 
   for line=lines,linee do
     local tx = editor:GetLine(line)
@@ -151,6 +152,8 @@ function MarkupStyle(editor, lines, linee)
     local from = 1
     local off = -1
 
+    local wrapped = editor:WrapCount(line)
+
     while from do
       tx = string.sub(tx,from)
       local f,t,w,mark = ismarkup(tx)
@@ -181,6 +184,17 @@ function MarkupStyle(editor, lines, linee)
       end
       from = t and (t+1)
     end
+
+    -- has this line changed its wrapping because of invisible styling?
+    if wrapped > 1 and editor:WrapCount(line) < wrapped then needfix = true end
   end
   editor:StartStyling(es, 31)
+
+  -- if any wrapped lines have changed, then reset WrapMode to fix the drawing
+  if needfix then
+    -- this fixes an issue with duplicate lines in Scintilla when
+    -- invisible styles hide some of the content that would be wrapped.
+    local wrapmode = editor:GetWrapMode()
+    if wrapmode ~= wxstc.wxSTC_WRAP_NONE then editor:SetWrapMode(wrapmode) end
+  end
 end