This file records noteworthy changes.
+1.5.7 (29 March 2010)
+* Fixed a bug in the GCD code (infinite loop in pgcd()).
+* Fixed a bug in atan2() (division by zero error for atan2(x,0) if x is a
+ negative and composite term).
+* Products now correctly set info_flags::negative and info_flags::negint.
+
+1.5.6 (28 January 2010)
+* Fixed compile problem with gcc 3.4.
+* Improved excompiler: The ginac-excompiler script will only be installed if
+ excompiler is supported and enabled.
+
+1.5.5 (04 November 2009)
+* Correct libtool versioning.
+
1.5.4 (02 November 2009)
* Default parser now can again read in user defined classes.
* Add mul::info() and add::info() support for numeric info_flags (GiNaC now can