- Changed variable type of the plugin_t "type" member from enum to Bit16u.
- Added support for returning device flags with the new mode PLUGIN_FLAGS in
the plugin entry functions. It is currently only used for devices that can
be connected to a PCI slot.
- Code cleanup in core device plugins: checking type no longer necessary.
- The "non-plugin" mode now also uses the "loadtype" member of plugin_t.
TODO: Change PCI slot options to bx_param_enum_c and build the choices list
using the new capabilities of the plugin API.