Make MetaData available to the library, respect it in window_init

This adds a new variable and macro to globals.h -- the macro is APP_INFO and it references the external variable __pbl_app_info; which the PBL_APP_INFO macro defines.

It also makes it so that the Window class' is_fullscreen is handled properly for the given app info flags.

Additionally, I make it so that the window's bounds get correctly resized if it's made fullscreen ( or made not full-screen. )