strings - bitwise_xor,  bitwise_not
strings - bitwise_xor,  bitwise_not

* disallow any non-fixed_8 encodings in string_bitwise_{xor,not}
* throw real_exception
* clean code a bit


git-svn-id: 6e74a02f85675cec270f5d931b0f6998666294a3@9997 d31e2699-5ff4-0310-a27c-f18f2fbe73fe

tkob/parrot,fernandobrito/parrot,tewk/parrot-select,gitster/parrot,parrot/parrot,FROGGS/parrot,gagern/parrot,tewk/parrot-select,youprofit/parrot,youprofit/parrot,FROGGS/parrot,gagern/parrot,FROGGS/parrot,fernandobrito/parrot,parrot/parrot,FROGGS/parrot,FROGGS/parrot,tewk/parrot-select,parrot/parrot,tewk/parrot-select,tkob/parrot,gitster/parrot,youprofit/parrot,youprofit/parrot,FROGGS/parrot,FROGGS/parrot,tewk/parrot-select,tewk/parrot-select,gitster/parrot,gagern/parrot,tkob/parrot,youprofit/parrot,tkob/parrot,tkob/parrot,tkob/parrot,fernandobrito/parrot,gagern/parrot,tewk/parrot-select,parrot/parrot,fernandobrito/parrot,gitster/parrot,parrot/parrot,gagern/parrot,gitster/parrot,gitster/parrot,tkob/parrot,gagern/parrot,fernandobrito/parrot,FROGGS/parrot,tkob/parrot,fernandobrito/parrot,gagern/parrot,youprofit/parrot,fernandobrito/parrot,youprofit/parrot,youprofit/parrot,gitster/parrot