CHANGELOG update

CHANGELOG

@@ -5,6 +5,17 @@
 Changelog
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+Release X
+--------------------------------------------------------------------------------
+
+* Generalize particle scoring and rotamer construction in sidechain module.
+  This simplifies the addition of other scoring functions in the future.
+  Be aware of breaking changes introduced in the process!
+  (SCWRLRotamerConstructor -> SCWRL4RotamerConstructor, changed interface of
+  Particle class).
+* Several minor bug fixes, improvements, and speed-ups  
+
+
 Release 1.3.0
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