FXLoad 2.1.0

Changes:

• CLI now uses subcommands (list, load_ram, and load_rom) instead of having everything lumped together. This should make the CLI easier to use
• New list feature allows listing devices without doing anything else
• Improve help for --type option
• Bugfix: selecting devices by bus/device number didn't work if there was a device with 0000:0000 vid:pid connected
• Bugfix: libusb warnings will no longer show up in the device list (warnings are ignored until we actually try to open the device now)