Reduce unnecessary COW on Vector by make writing explicit

This commit makes operator[] on Vector const and adds a write proxy to it.  From
now on writes to Vectors need to happen through the .write proxy. So for
instance:

Vector<int> vec;
vec.push_back(10);
std::cout << vec[0] << std::endl;
vec.write[0] = 20;

Failing to use the .write proxy will cause a compilation error.

In addition COWable datatypes can now embed a CowData pointer to their data.
This means that String, CharString, and VMap no longer use or derive from
Vector.

_ALWAYS_INLINE_ and _FORCE_INLINE_ are now equivalent for debug and non-debug
builds. This is a lot faster for Vector in the editor and while running tests.
The reason why this difference used to exist is because force-inlined methods
used to give a bad debugging experience. After extensive testing with modern
compilers this is no longer the case.

1 files changed, 1 insertions, 1 deletions

diff --git a/editor/plugins/asset_library_editor_plugin.cpp b/editor/plugins/asset_library_editor_plugin.cpp
index 505dd4ab76..e98dfceb90 100644
--- a/editor/plugins/asset_library_editor_plugin.cpp
+++ b/editor/plugins/asset_library_editor_plugin.cpp
@@ -197,7 +197,7 @@ void EditorAssetLibraryItemDescription::set_image(int p_type, int p_index, const
 
 			for (int i = 0; i < preview_images.size(); i++) {
 				if (preview_images[i].id == p_index) {
-					preview_images[i].image = p_image;
+					preview_images.write[i].image = p_image;
 					if (preview_images[i].button->is_pressed()) {
 						_preview_click(p_index);
 					}