update changelog for next release 3.5.1.
# JavaSMT ChangeLog
+## JavaSMT 3.5.1
+
+### Improvements and Fixes:
+ - improve interpolation error detection for MathSAT5
+ - fix simplification procedure for MathSAT5
+ - improve interrupt detection for Z3
+ - fix quantifier elimination for Z3
+
## JavaSMT 3.5.0
This release mostly contains updated solvers,
