Upped the serialized version of AbstractElementMirror, added many cmdline interpreter features.

Extensions will need to recompile to make use of the new cache format, but previously compiled extensions will work, as a new cache will be created when the first fails.

The cmdline interpreter now is fully featured as a shell. Prompts, function completion, Ctrl+C, etc, are all supported, and several new functions have been added. On linux systems, a man page for "mscript" is also installed. To make full use of the new features, unix cmdline users will need to re-run java -jar CH.jar install-cmdline.