Added better support for code blocks meant for portions of the toolchain.
    :- begin_asp. /   :- end_asp.
    #begin_asp    /   #end_asp
    :- begin_lua. /   :- end_lua.
    #begin_lua    /   #end_lua.
    :- begin_f2lp./   :- end_f2lp.
    #begin_f2lp   /   #end_f2lp
Added an example of this (examples/etc/code_blocks).