(checkUnset): Rename to checkBlank.
	(setValue, setvalue, setException, setThnk): New methods.
	(getValue): Changes to handle new functionality.
	(print): Add overload.
	(toString): New method.

	* LangObjType.java (promiseType): New static field.
	(PROMISE_TYPE_CODE): New constant.
	(getConstructorType): New method.

	* CompileInvoke.java (validateApplyInvoke): If type is LangObjType,
	call getConstructorType.

	* misc.scm (promise-set-value!, promise-set-alias!,
	promise-set-exception!, promise-set-thunk!): New procedures.

	* standard/Scheme.java (initScheme): Declare promise-set-value!,
	promise-set-alias!, promise-set-exception!, and promise-set-thunk!.
	(getTypeName): Change binding for "promise".

	* promise1.scm: New testcase.
	* Makefile.am: Update accordingly.