Rename conceal mode to separator

lua/hardline/common.lua

@@ -33,7 +33,7 @@ function M.get_state(section)
     return mode.state
   end
   if section.class == 'bufferline' then
-    if section.conceal then return 'conceal' end
+    if section.separator then return 'separator' end
     local state = section.current and 'current' or 'background'
     if section.modified then state = string.format('%s_modified', state) end
     return state

lua/hardline/themes/default.lua

@@ -92,7 +92,7 @@ return {
     inactive = inactive,
   },
   bufferline = {
-    conceal = {
+    separator = {
       guifg = colors.comment_grey.gui,
       guibg = colors.black.gui,
       ctermfg = colors.comment_grey.cterm,

lua/hardline/themes/one.lua

@@ -92,7 +92,7 @@ return {
     inactive = inactive,
   },
   bufferline = {
-    conceal = {
+    separator = {
       guifg = colors.comment_grey.gui,
       guibg = colors.black.gui,
       ctermfg = colors.comment_grey.cterm,