optimization and fixes

src_main/containers/pimap.h

@@ -197,6 +197,7 @@ public:
 	const T at(const Key & key) const {return (*this)[key];}
 	
 	PIMap<Key, T> & operator <<(const PIMap<Key, T> & other) {
+		if (&other == this) return *this;
 		if (other.isEmpty()) return *this;
 		if (other.size() == 1) {insert(other.pim_index[0].key, other.pim_content[0]); return *this;}
 		if (other.size() == 2) {insert(other.pim_index[0].key, other.pim_content[0]); insert(other.pim_index[1].key, other.pim_content[1]); return *this;}