refactor: add 'const' qualifier for content units

src/content/Content.hpp

@@ -65,14 +65,6 @@ public:
         return defs[id];
     }
 
-    [[deprecated]]
-    inline T* getWriteable(blockid_t id) const { // TODO: remove
-        if (id >= defs.size()) {
-            return nullptr;
-        }
-        return defs[id];
-    }
-
     inline const T& require(blockid_t id) const {
         return *defs.at(id);
     }
@@ -111,14 +103,14 @@ public:
     ContentUnitDefs(UptrsMap<std::string, T> defs) : defs(std::move(defs)) {
     }
 
-    T* find(const std::string& id) const {
+    const T* find(const std::string& id) const {
         const auto& found = defs.find(id);
         if (found == defs.end()) {
             return nullptr;
         }
         return found->second.get();
     }
-    T& require(const std::string& id) const {
+    const T& require(const std::string& id) const {
         const auto& found = defs.find(id);
         if (found == defs.end()) {
             throw std::runtime_error("missing content unit " + id);

src/logic/scripting/lua/libblock.cpp

@@ -360,7 +360,7 @@ static int l_raycast(lua::State* L) {
             for (int i = 0; i < addLen; i++) {
                 lua::rawgeti(L, i + 1, 5);
                 auto blockName = std::string(lua::tostring(L, -1));
-                Block* block = content->blocks.find(blockName);
+                const Block* block = content->blocks.find(blockName);
                 if (block != nullptr) {
                     filteredBlocks.insert(block->rt.id);
                 }

src/logic/scripting/lua/libentity.cpp

@@ -127,7 +127,7 @@ static int l_raycast(lua::State* L) {
             for (int i = 0; i < addLen; i++) {
                 lua::rawgeti(L, i + 1, 6);
                 auto blockName = std::string(lua::tostring(L, -1));
-                Block* block = content->blocks.find(blockName);
+                const Block* block = content->blocks.find(blockName);
                 if (block != nullptr) {
                     filteredBlocks.insert(block->rt.id);
                 }

src/objects/Entities.cpp

@@ -75,7 +75,7 @@ static sensorcallback create_sensor_callback(Entities* entities) {
 }
 
 static void initialize_body(
-    EntityDef& def, Rigidbody& body, entityid_t id, Entities* entities
+    const EntityDef& def, Rigidbody& body, entityid_t id, Entities* entities
 ) {
     body.sensors.resize(def.radialSensors.size() + def.boxSensors.size());
     for (auto& [i, box] : def.boxSensors) {
@@ -111,7 +111,7 @@ static void initialize_body(
 }
 
 entityid_t Entities::spawn(
-    EntityDef& def,
+    const EntityDef& def,
     glm::vec3 position,
     dynamic::Map_sptr args,
     dynamic::Map_sptr saved,

src/objects/Entities.hpp

@@ -202,7 +202,7 @@ public:
     );
 
     entityid_t spawn(
-        EntityDef& def,
+        const EntityDef& def,
         glm::vec3 position,
         dynamic::Map_sptr args = nullptr,
         dynamic::Map_sptr saved = nullptr,