Fix bug 529770 caused by non-const copy constructor.

--- libmems-1.6_p1/libMems/Aligner.cpp
+++ libmems-1.6_p1/libMems/Aligner.cpp
@@ -939,7 +939,7 @@
 	MatchLeftEndComparator( unsigned seq = 0 ){
 		m_seq = seq;
 	}
-	MatchLeftEndComparator( MatchLeftEndComparator& msc ){
+	MatchLeftEndComparator( const MatchLeftEndComparator& msc ){
 		m_seq = msc.m_seq;
 	}
 	// TODO??  make this do a wraparound comparison if all is equal?
--- libmems-1.6_p1/libMems/Aligner.h
+++ libmems-1.6_p1/libMems/Aligner.h
@@ -49,7 +49,7 @@
 	LabeledMemComparator( uint seq ){
 		m_seq = seq;
 	}
-	LabeledMemComparator( LabeledMemComparator& lmc ){
+	LabeledMemComparator( const LabeledMemComparator& lmc ){
 		m_seq = lmc.m_seq;
 	}
 	boolean operator()(const LabeledMem& a, const LabeledMem& b) const{