make internal-use environments explicit; save hash/size info for new.env

...com/oracle/truffle/r/nodes/builtin/base/EnvFunctions.java

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

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

...nodes/src/com/oracle/truffle/r/nodes/control/ForNode.java

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

...e/src/com/oracle/truffle/r/runtime/data/RDataFactory.java

...me/src/com/oracle/truffle/r/runtime/env/REnvironment.java