fix: list MAME's hash, plugins and floppy sounds

The libretro core passes system/mame/{hash,plugins,samples} (retro_init.cpp:111-155). Software lists are required in mamemess, where softlists are on by default. The trees and the 19 floppy samples are collected from libretro/mame at the pin.

bios/Other/mame/plugins/timecode/plugin.json

@@ -0,0 +1,10 @@
+{
+	"plugin": {
+		"name": "timecode",
+		"description": "Timecode recorder plugin",
+		"version": "0.0.1",
+		"author": "Vas Crabb",
+		"type": "plugin",
+		"start": "false"
+	  }
+}