Improved internal data structure of tree-view

Completed work -

• Seg fault while toggling show-hidden.
• implement get paths for pattern
• Implement searching. (Set Job)
• clean collapsed folders ? to reduce mem usage.
• valgrind testing (Fixed found mem leaks)

TODO (after Merge) (From !352 (merged))

• #1144 (closed) - Properly define and implement the drag and drop of expanded files.
• #1146 (closed) - Improve Thunar responsiveness (remove freezes) when opening 10000+ files.
  • Explore the various solutions. Make things more async.
  • Investigate the cause of the freeze.
• #1145 (closed) - XL & XL+ thumbnails.
  • May need a rewrite of thumbnailing.
• #1148 (closed) - Expanding folders in single click mode will activate them
• #1149 (closed) - Select files after action in list view
• #1156 (closed) - Reload is called once per subfolder
• #1179 (closed) - Failure to remove file from tree-view-model in some cases