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, 3 insertions, 3 deletions

diff --git a/scene/resources/texture.cpp b/scene/resources/texture.cpp
index 5fb9f79a1e..c8d12b88fc 100644
--- a/scene/resources/texture.cpp
+++ b/scene/resources/texture.cpp
@@ -1039,7 +1039,7 @@ bool LargeTexture::has_alpha() const {
 void LargeTexture::set_flags(uint32_t p_flags) {
 
 	for (int i = 0; i < pieces.size(); i++) {
-		pieces[i].texture->set_flags(p_flags);
+		pieces.write[i].texture->set_flags(p_flags);
 	}
 }
 
@@ -1065,13 +1065,13 @@ int LargeTexture::add_piece(const Point2 &p_offset, const Ref<Texture> &p_textur
 void LargeTexture::set_piece_offset(int p_idx, const Point2 &p_offset) {
 
 	ERR_FAIL_INDEX(p_idx, pieces.size());
-	pieces[p_idx].offset = p_offset;
+	pieces.write[p_idx].offset = p_offset;
 };
 
 void LargeTexture::set_piece_texture(int p_idx, const Ref<Texture> &p_texture) {
 
 	ERR_FAIL_INDEX(p_idx, pieces.size());
-	pieces[p_idx].texture = p_texture;
+	pieces.write[p_idx].texture = p_texture;
 };
 
 void LargeTexture::set_size(const Size2 &p_size) {