Remeber initial user text for hidden suggestions

When using hidden suggestions remember the text user was typing when
navigating suggestions.

Ensure also that in the previously searched expressiosn we have no
duplicate entries.

data/core/commands/findreplace.lua

@@ -41,6 +41,16 @@ local function update_preview(sel, search_fn, text)
   end
 end
 
+
+local function insert_unique(t, v)
+  local n = #t
+  for i = 1, n do
+    if t[i] == v then return end
+  end
+  t[n + 1] = v
+end
+
+
 local function find(label, search_fn)
   last_view, last_sel, last_finds = core.active_view,
     { core.active_view.doc:get_selection() }, {}
@@ -51,7 +61,7 @@ local function find(label, search_fn)
 
   core.command_view:set_hidden_suggestions()
   core.command_view:enter(label, function(text, item)
-    table.insert(core.previous_find, text)
+    insert_unique(core.previous_find, text)
     core.status_view:remove_tooltip()
     if found then
       last_fn, last_text = search_fn, text
@@ -80,12 +90,13 @@ local function replace(kind, default, fn)
   core.status_view:show_tooltip(get_find_tooltip())
   core.command_view:set_hidden_suggestions()
   core.command_view:enter("Find To Replace " .. kind, function(old)
+    insert_unique(core.previous_find, old)
     core.command_view:set_text(old, true)
 
     local s = string.format("Replace %s %q With", kind, old)
     core.command_view:set_hidden_suggestions()
     core.command_view:enter(s, function(new)
-      table.insert(core.previous_replace, new)
+      insert_unique(core.previous_replace, new)
       local n = doc():replace(function(text)
         return fn(text, old, new)
       end)