NextZ80

I have added support for eZ80 instructions to your core (all instructions which works in Z80 mode of eZ80). Processor works perfectly (without any bugs for instructions which I use). Basically I start my changes on 7th SVN revision of your project. Later I backport all your later changes. There is fixed bug with R register which was kept unchanged while processor executing HALT instruction (original Z80 executes HALT instruction as infinite NOP instruction, so R changes each 4 clocks). Sources you may download from here: https://yadi.sk/d/417xl6Gn5fE0LQ

Patch around SVN trunk: https://yadi.sk/d/TU0MHczdDQ8gSA