MISC: Various small fixes (#574)

* ns.ls filter can include leading slash in filename
* scp from terminal accepts multiple filenames
* terminal displays root / instead of ~ as base
* cd with no args returns to root

src/NetscriptFunctions.ts

@@ -902,7 +902,7 @@ export const ns: InternalAPI<NSFull> = {
     ];
 
     if (!substring) return allFilenames.sort();
-    return allFilenames.filter((filename) => filename.includes(substring)).sort();
+    return allFilenames.filter((filename) => ("/" + filename).includes(substring)).sort();
   },
   getRecentScripts: () => (): RecentScript[] => {
     return recentScripts.map((rs) => ({