Let users attach multiple devices with -D option to emulator.

[hach-que]

Currently the emulator starts with default hardware attached; it is only possible to attach specific hardware or multiple instances of the same hardware using the debugger command line interface.

The -D option should also allow passing of parameters to hardware. An invocation of the emulator may look like:

dtemu -Dlem1802 -Dlem1802 -Dm45fd=disk.img

which would start the emulator with 2 LEM1802 devices and the M45FD pointed to a disk image called 'disk.img'.

Once this functionality is implemented, the emulator should default to loading no devices; instead it will show a warning if no devices are specified at start.