Java backend: added more precise error message
Java backend: fixed the bug that functions on the RHS of a rule stay unevaluated after apply the rule
Java backend: several minor fixes
tried to fix the bug related to Context#labels
Java backend: fixed a missing import
Java backend: reverted previous attempt to fix the case of having ground functions on the RHS of a rule
Java backend: fixed the algorithm that checks if the result of unification is pattern matching
temporary changes
Java backend: added check to detect KLabel clash when constructing new KLabelConstant's
Java backend: fixed the algorithm that checks if a rule application is driven by pattern matching
Java backend: fixed definitions that have KLabel clashes
Java backend: commented out an assertion in SymbolicRewriter to make logik work
Java backend: fixed a bug