improvements to editor

[pollend]

Here are just a few ideas to give the editor some additional functionality:

1. A free-move toggleable camera like in Map Viewer.
2. Toggleable physics so the game doesn't have to deal with falling objects when the map loads.
3. Configurable shortcuts.
4. CTRL+C and CTRL+V shortcut capable of copying and pasting objects between multiple maps.
5. Search bar for browsing entities, static objects, particles and sounds by name.
6. Planes casting shadows in the editor when Cast Shadows on them is ticked.
7. Functional "Align To Word Coords" on planes even when the plane is rotated 90 degrees.
8. Fixed weird duplication bug where the Editor duplicates an object two times instead of once.
9. A "Play This Level button" which starts the game with the map loaded.
10. A "Generate Map Cache" button which deletes and generates a new map_cache file.
11. A "Generate Pathnodes" button which generates pathnodes file for the map.
12. A '+' button on entities that opens in-window instance of the model editor with that specific entity loaded. (same for particle systems)
13. When objects of the same type are selected, allow editing the variables of all at the same time. (e.g. selecting entities of type 'Grab' let's me enable StaticPhysics on all selected with one tickbox)
14. Fix Compounds disappearing when Undo is pressed.
15. When entities are selected also highlight the hitboxes not just the mesh.