Added command line options --cuda and --cuda-loader.

src/config.json

@@ -38,6 +38,10 @@
         "cn/0": false,
         "cn-lite/0": false
     },
+    "cuda": {
+        "enabled": false,
+        "loader": null,
+    },
     "donate-level": 5,
     "donate-over-proxy": 1,
     "log-file": null,
@@ -64,4 +68,4 @@
     "syslog": false,
     "user-agent": null,
     "watch": true
-}
+}