Adjusted the bus cycles timing to be equivalent to those measured on a real Z80 at 4 MHz.

Done some improvements to the binary editor, it's a bit easier to use and there's now a help on screen.

The Intel Hex loader now works if we send bytes slowly enough. On linux, I use the command: "pv -L 10 myhexfile.hex > /dev/ttyUSB0", which transmit 10 bytes/sec.

I will try to implement interrupt or DMA on the serial port.