Added 'shortcutParam' argument to init() method declaration.

public static native void init(int dpi, String deviceType, String languageRegion, String apkPath, String dataDir, String externalDir, String libraryDir, String shortcutParam, String installID, boolean useOpenSL);
- Added key to get shortcut parameter.
public static final String SHORTCUT_EXTRA_KEY = "org.ppsspp.ppsspp.Shortcuts";

- Added code to get shortcut parameter from intent.
String shortcutParam = getIntent().getStringExtra(SHORTCUT_EXTRA_KEY);

- Call NativeApp.init() with shortcutParam argument.
NativeApp.init(dpi, deviceType, languageRegion, apkFilePath, dataDir, externalStorageDir, libraryDir, shortcutParam, installID, useOpenSL);
- Added jshortcutParam parameter to libnative_NativeApp_init.

- If shortcut_param is not empty, pass it as additional varargs argument to NativeInit() method.
const char *argv[3] = {app_name.c_str(), shortcut_param.c_str(), 0};
NativeInit(2, argv, user_data_path.c_str(), externalDir.c_str(), installID.c_str());

- NativeInit() is expected to treat extra argument as boot_filename, which in turn will start game immediately.
- Removed SHORTCUT_EXTRA_KEY and shortcut query out of NativeActivity class.

- Added String shortcutParam member & setShortcutParam() method. This will be set from other class.
Merge pull request #186 from valef/android-shortcut

Android homescreen shortcut - native part