Parsing data & settings XMLs during splash screen.

Removed ParseXmlTask which is now needless (parsing takes place in Thread).
Removed parsing from MainActivity.
Only one background thread running at a time in SplashActivity.
Splash duration can be set from options XML.
SplashActivity can read data and options XMLs from external source. By default external data is read from .myguide/data2.xml and settings from .myguide/config.xml (both from external storage, eg. sdcard or internal 2nd partition). SplashActivity first tries reading from external source then, if failed, fallbacks to resources.