Fix mem leak in IfcSpfStream (not closed upon destruction), make Entity's dtor virtual.

src/ifcparse/IfcParse.cpp

@@ -127,6 +127,11 @@ IfcSpfStream::IfcSpfStream(void* data, int l) {
 	len = l;	
 }
 
+IfcSpfStream::~IfcSpfStream()
+{
+	Close();
+}
+
 void IfcSpfStream::Close() {
 #ifdef BUF_SIZE
 	if ( paging ) fclose(stream);

src/ifcparse/IfcParse.h

@@ -248,7 +248,7 @@ namespace IfcParse {
 		unsigned int offset;		
 		Entity(unsigned int i, IfcFile* t);
 		Entity(unsigned int i, IfcFile* t, unsigned int o);
-		~Entity();
+		virtual ~Entity();
 		IfcEntityList::ptr getInverse(IfcSchema::Type::Enum type, int attribute_index);
 		void Load(std::vector<unsigned int>& ids, bool seek=false) const;
 		Argument* getArgument (unsigned int i);

src/ifcparse/IfcSpfStream.h

@@ -64,6 +64,7 @@ namespace IfcParse {
 		IfcSpfStream(const std::string& fn);
 		IfcSpfStream(std::istream& f, int len);
 		IfcSpfStream(void* data, int len);
+		~IfcSpfStream();
 		/// Returns the character at the cursor 
 		char Peek();
 		/// Returns the character at specified offset