WiiFlow compatibility for autolauch games. (FIX94)

[saulfabregwiivc]

From http://github.com/FIX94/Wii64

Adds arguments support for autolaunch games via WiiFlow.

In the meta.xml file, the arguments for use are: <arguments> <arg>{device}:/{path_of_ROM}</arg> <arg>{ROM_file}</arg> </arguments>

For example: <arguments> <arg>sd:/apps/wii64_singlegame/rom</arg> <arg>SuperMario64.z64</arg> </arguments>

This will be useful for WiiFlow, and other game launchers including making custom simple game loaders along with forwarder channels, specially since Wii64 is the only N64 emulator for Wii which has Rice GFX for that problematic games that wouldn't run in glN64 GFX. Also I added a small change which allows the user to change the ROM even after using autoboot.

This code i'm adding will not interfiere with other arguments that can be used also in meta.xml (such CountPerOp, FBTex, ScreenMode, etc.)

Thanks! @saulfabregwiivc