Update to SML/NJ 110.73

SML/NJ 110.73 provides a number of new library features,
including a new library for working with HTML 4, as well
as many bug fixes.

Details:

CM:
  + Added boolean literals (true and false) to the
    conditional-expression syntax in CM. Thus, you can write

        #if true structure Foo #endif

    in a CM file. This change is meant to make it easier to use
    autoconf to configure the build process of an SML
    application.
ML-Yacc:
  + Fixed ml-yacc examples to respect the changed signatures
    with respect to TextIO.inputLine.

SML/NJ Library:
  + Added findExe function to PathUtil module.
  + Modified the implementation of GetOpt.usageInfo so that if
    the help string has embedded newlines, then the extra lines
    are properly indented.
  + Changed the interface of JSONStreamParser to support both
    parsing files and TextIO.instreams.
  + Added HTML4 library.
  + Fixed bug in hashed cons library (bug #55).
  + Added array iterators to DynamicArray module.
Concurrent ML:
  + The paths used to specify the CML versions of libraries in
    a CM file have been rationalized (bug #68)

        $cml/basis.cm -- the CML version of $/basis.cm
        $cml/cml.cm -- core CML features
        $cml/cml-lib.cm -- CML library code
        $cml/trace-cml.cm -- TraceCML library for debugging
        $cml/smlnj-lib.cm -- CML version of the $/smlnj-lib.cm library
        $cml/inet-lib.cm -- CML version of the $/inet-lib.cm library
        $cml/unix-lib.cm -- CML version of the $/unix-lib.cm library

    Note that the old naming scheme is still supported, but may
    be removed in some future version.
  + Added Barriers module to CML.
  + Fixed the Win32 socket and polling implementation to work
    correctly with CML. Signature of poll was wrong and didn't
    handle sockets at all.
MLRISC:
  + Added support for the RTDSC and RTDSCP instructions to the
    amd64 code generator.

(asau)