fixed one test which was still expecting \b word terminators in the generated lex table: that jison 'feature' has been killed in recent work as it only confuses.
fixed make dependencies and added bootstrapping actions so that the sequence `make superclean; make` will work while the 'superclean' target will kill all generated files
added generated files again as anyone who wishes to run jison 'out of the box' needs those.
add support for a 'action header chunk' which is a block of code that is included at the *top* of the actionHandler. You may use such an action block for example to define local variables which are used in one or more production action blocks. Format / example:

    %{ /* this is not an 'action header chunk': this chunk is appended to the Parser class itself. */ %}
    %start begin
    %%
    %{
      /* this is the new 'action header chunk': it is included in the performAction handler. */
      /* WARNING: this chunk (or series of chunks) MUST be placed before the FIRST production/rule! */
      /*          (otherwise it would potentially be confused with a production action block) */

      var local1; // variables used in productions' actions
    %}
    begin: A
      %{
        local1 = $1; // use local var, declared in 'action header chunk'
        $$ = local1 + 'xyz';
      %}
    %%