improve path handling

test/assets/customdir/tsfile1.js

@@ -0,0 +1,2 @@
+var something = "something";
+//# sourceMappingURL=tsfile1.js.map

test/assets/customdir/tsfile1.js.map

@@ -0,0 +1 @@
+{"version":3,"file":"tsfile1.js","sourceRoot":"","sources":["tsfile1.ts"],"names":[],"mappings":"AAAA,IAAI,SAAS,GAAG,WAAW,CAAC"}

test/assets/customdir/tsfile1.ts

@@ -0,0 +1 @@
+var something = "something";

test/assets/npmts.json

@@ -1,7 +1,7 @@
 {
   "mode":"custom",
   "ts":{
-    "./customdir/custom.ts":"./customcompiled.js"
+    "./customdir/*.ts":"./"
   },
   "typings":[
     "./customdir"

test/assets/tsfile1.d.ts

@@ -0,0 +1 @@
+declare var something: string;

test/assets/tsfile1.js

@@ -0,0 +1,3 @@
+#!/usr/bin/env node
+
+var something = "something";