build system updates, for mobile builds

- main build.py will optionally build mobile. removed now obsolete mobile build scripts and symbolic links
- external resource URL is now optional - it's no longer needed by the regular builds

mobile/.gitignore

@@ -6,3 +6,4 @@ gen/
 libs/
 proguard-project.txt
 local.properties
+assets/iitc.js

mobile/assets/iitc.js

@@ -1 +0,0 @@
-../../build/local8000/total-conversion-build.user.js

mobile/build_mobile.sh

@@ -1,10 +0,0 @@
-#!/bin/sh
-
-set -e
-
-cd `dirname "$0"`
-cd ..
-./build.py local8000
-cd build/local8000
-cd ../../mobile
-ant debug