Add notes about the new ENGINE functionality.

         *) applies to 0.9.6a (/0.9.6b) and 0.9.7

         +) applies to 0.9.7 only

  +) Changes to the "openssl engine" utility to include;

     - verbosity levels ('-v', '-vv', and '-vvv') that provide information

       about an ENGINE's available control commands.

     - executing control commands from command line arguments using the

       '-pre' and '-post' switches. '-post' is only used if '-t' is

       specified and the ENGINE is successfully initialised. The syntax for

       the individual commands are colon-separated, for example;

	 openssl engine chil -pre FORK_CHECK:0 -pre SO_PATH:/lib/test.so

     [Geoff]

  +) New dynamic control command support for ENGINEs. ENGINEs can now

     declare their own commands (numbers), names (strings), descriptions,

     and input types for run-time discovery by calling applications. A

     subset of these commands are implicitly classed as "executable"

     depending on their input type, and only these can be invoked through

     the new string-based API function ENGINE_ctrl_cmd_string(). (Eg. this

     can be based on user input, config files, etc). The distinction is

     that "executable" commands cannot return anything other than a boolean

     result and can only support numeric or string input, whereas some

     discoverable commands may only be for direct use through

     ENGINE_ctrl(), eg. supporting the exchange of binary data, function

     pointers, or other custom uses. The "executable" commands are to

     support parameterisations of ENGINE behaviour that can be

     unambiguously defined by ENGINEs and used consistently across any

     OpenSSL-based application. Commands have been added to all the

     existing hardware-supporting ENGINEs, noticeably "SO_PATH" to allow

     control over shared-library paths without source code alterations.

     [Geoff]

  +) Changed all ENGINE implementations to dynamically allocate their

     ENGINEs rather than declaring them statically. Apart from this being

     necessary with the removal of the ENGINE_FLAGS_MALLOCED distinction,

     this also allows the implementations to compile without using the

     internal engine_int.h header.

     [Geoff]

  +) Minor adjustment to "rand" code. RAND_get_rand_method() now returns a

     'const' value. Any code that should be able to modify a RAND_METHOD

     should already have non-const pointers to it (ie. they should only

     modify their own ones).

     [Geoff]

  +) Made a variety of tweaks to the ENGINE code.

  +) Made a variety of little tweaks to the ENGINE code.

     - "atalla" and "ubsec" string definitions were moved from header files

       to C code. "nuron" string definitions were placed in variables

       rather than hard-coded - allowing parameterisation of these values