Remove files from project list when collapsed

Only in limited files mode. We now symmetrically add the files if
a folder is expanded and remove them if it is collapsed.

data/core/init.lua

@@ -323,16 +323,17 @@ local function rescan_project_subdir(dir, filename_rooted)
 end
 
 
-function core.scan_project_subdir(dir, filename)
+function core.update_project_subdir(dir, filename, expanded)
   local index, n, file = project_subdir_bounds(dir, filename)
   if index then
-    local new_files = get_directory_files(dir, dir.name, PATHSEP .. filename, {})
+    local new_files = expanded and get_directory_files(dir, dir.name, PATHSEP .. filename, {}) or {}
     files_list_replace(dir.files, index, n, new_files)
     dir.is_dirty = true
     return true
   end
 end
 
+
 -- Find files and directories recursively reading from the filesystem.
 -- Filter files and yields file's directory and info table. This latter
 -- is filled to be like required by project directories "files" list.

data/plugins/treeview.lua

@@ -216,9 +216,7 @@ function TreeView:on_mouse_pressed(button, x, y, clicks)
     else
       hovered_item.expanded = not hovered_item.expanded
       if hovered_item.dir.files_limit then
-        if hovered_item.expanded then
-          core.scan_project_subdir(hovered_item.dir, hovered_item.filename)
-        end
+        core.update_project_subdir(hovered_item.dir, hovered_item.filename, hovered_item.expanded)
         print("DEBUG setting show flag to", hovered_item.expanded)
         core.project_subdir_set_show(hovered_item.dir, hovered_item.filename, hovered_item.expanded)
       end