Add BOM skip and fix mtl parsing (#6253)

* Add BOM skip and fix mtl parsing
* Remove old code
* Fix #5635
* Add all attributes to ObjFileData
---------

Co-authored-by: Kim Kulling <kimkulling@users.noreply.github.com>

code/AssetLib/Obj/ObjFileParser.cpp

@@ -121,6 +121,13 @@ void ObjFileParser::parseFile(IOStreamBuffer<char> &streamBuffer) {
         m_DataItEnd = buffer.end();
         mEnd = &buffer[buffer.size() - 1] + 1;
 
+        if (processed == 0 && std::distance(m_DataIt, m_DataItEnd) >= 3 &&
+            static_cast<unsigned char>(*m_DataIt) == 0xEF &&
+            static_cast<unsigned char>(*(m_DataIt + 1)) == 0xBB &&
+            static_cast<unsigned char>(*(m_DataIt + 2)) == 0xBF) {
+            m_DataIt += 3; // skip BOM
+        }
+
         // Handle progress reporting
         const size_t filePos(streamBuffer.getFilePos());
         if (lastFilePos < filePos) {