(TODO: find a way to call plugin_fini() for non-core devices if plugins are
disabled)
- set the device pointers back to stubs after unloading plugins
- added debug message "Exit" in all device plugin destructors
bochs.h already not include iodev.h which reduces compilation dependences for almost all cpu and fpu files, now cpu files will not be recompiled if iodev includes was changed
Unallowed cases are now handled in devices.cc and cause a BX_ERROR.
- io_len mask fixed and unnecessary io_len checks removed in
* devices.cc
* extfpuirq.cc
* gameport.cc
* ne2k.cc
* pit.cc
* pit_wrap.cc (i/o register function calls replaced by DEV_* macro calls)
- TODO: implement this in all other devices
