Merge branch 'master' into feature/r-3.3.0

...ine/src/com/oracle/truffle/r/engine/TruffleRLanguage.java

...ibrary/src/com/oracle/truffle/r/library/stats/Covcor.java

com.oracle.truffle.r.native/fficall/src/jni/base_rffi.c

...cle/truffle/r/nodes/builtin/base/S3DispatchFunctions.java

...s/src/com/oracle/truffle/r/nodes/access/ConstantNode.java

.../com/oracle/truffle/r/nodes/function/CallMatcherNode.java

...fle/r/nodes/function/signature/CombineSignaturesNode.java

...fi/src/com/oracle/truffle/r/runtime/ffi/jni/JNI_Base.java

.../src/com/oracle/truffle/r/runtime/ArgumentsSignature.java