Refactor texture overrides and add new features (#9600)

* Refactor texture overrides, and add new features:

- Texture overrides can support multiple targets in one line
- Texture override files can have comment lines
- Item images/wield images can be overridden

* Formatting changes

* Address soime feedback

- Pass vectors by const reference
- Log syntax errors as warnings
- Remove 'C' prefix from TextureOverrideSource

* Simplify override target checks with an inline helper function

* make linter happy

* Apply feedback suggestions

Co-Authored-By: rubenwardy <rw@rubenwardy.com>

* Remove remaining != 0 checks

* Update copyright notice

Co-authored-by: sfan5 <sfan5@live.de>
Co-authored-by: rubenwardy <rw@rubenwardy.com>

src/itemdef.h

@@ -26,6 +26,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <set>
 #include "itemgroup.h"
 #include "sound.h"
+#include "texture_override.h" // TextureOverride
 class IGameDef;
 class Client;
 struct ToolCapabilities;
@@ -157,6 +158,10 @@ public:
 		Client *client) const=0;
 #endif
 
+	// Replace the textures of registered nodes with the ones specified in
+	// the texture pack's override.txt files
+	virtual void applyTextureOverrides(const std::vector<TextureOverride> &overrides)=0;
+
 	// Remove all registered item and node definitions and aliases
 	// Then re-add the builtin item definitions
 	virtual void clear()=0;