- optimized storage for animation definitions.

Instead of allocating everything on the heap as single blocks, use a value TArray and allocate the frame arrays from the texture manager's memory arena, since lifetime of the data is identical.
Most importantly this avoids using a variable size array at the end of the struct.

src/common/textures/texturemanager.cpp

@@ -1615,7 +1615,7 @@ void FTextureManager::AddAlias(const char* name, FGameTexture* tex)
 //
 //==========================================================================
 
-FTextureID FTextureID::operator +(int offset) throw()
+FTextureID FTextureID::operator +(int offset) const noexcept(true)
 {
 	if (!isValid()) return *this;
 	if (texnum + offset >= TexMan.NumTextures()) return FTextureID(-1);