Gameini updates.

Updates gameinis for various us wiiware titles. How to Train Your Dragon
2 (wii), Opoona (wii), The Legend of Zelda: Collector's Edition (gc),
Super Mario Sunshine (gc), Super Monkey Ball 2  (gc) updated.
Fixes issues 7491, 7447 and 7581.
Core: Simplify Memory::GetString
Merge pull request #853 from lioncash/memmap

Core: Simplify Memory::GetString
Merge pull request #847 from Linktothepast/gameinis

Gameini updates.
Add headers required by XAudio2_7 to externals.

This makes all builds' audio compatible with downlevel Windows and removes
the need for developers to install the June 2010 DirectX SDK.