fix cumulative functions and add tests

...n/src/com/oracle/truffle/r/nodes/builtin/base/CumMax.java

...n/src/com/oracle/truffle/r/nodes/builtin/base/CumMin.java

.../src/com/oracle/truffle/r/nodes/builtin/base/CumProd.java

...n/src/com/oracle/truffle/r/nodes/builtin/base/CumSum.java

.../src/com/oracle/truffle/r/nodes/unary/CastDoubleNode.java

...src/com/oracle/truffle/r/nodes/unary/CastIntegerNode.java

...le.r.runtime/src/com/oracle/truffle/r/runtime/RError.java

...est/src/com/oracle/truffle/r/test/ExpectedTestOutput.test

...om/oracle/truffle/r/test/builtins/TestBuiltin_cummax.java

...om/oracle/truffle/r/test/builtins/TestBuiltin_cummin.java

...m/oracle/truffle/r/test/builtins/TestBuiltin_cumprod.java

...om/oracle/truffle/r/test/builtins/TestBuiltin_cumsum.java