Register luaopen_lush() in stdlibs so the lush table is available as a global. Users can now extend the shell by adding functions to lush.builtins. The OP_LUSH VM access via integer keys is preserved.
- #25: $VAR expansion in commands - #26: Shell abbreviations and user-extensible builtins - #27: $(cmd) subcommand syntax - #22: Updated with implementation details (in progress) - #7: Standardize status label