Guides quickspeech: quickly load and switch random audio speech

The demo scene doesn't need to be a separate resource from the guide, so I'm tidying it up and merging these two resources.

The demo scene was also updated to make use of the previously shared American Preset Pack. You can now choose 2 voices and they are instantly changeable.

Guide updated to reflect the changes in the demonstration scene using the new MacGruber's Logicbricks v14.

The new version makes the use of the quickspeech atom setup and audio assetbundles simpler and more flexible, taking away almost all caveats in the previous version's setup.

MacGruber's Early-Access Logicbricks v14 introduces new options for sounds in assetbundles. This allows simpler scalable setups and fewer caveats.
Added parts with v14 and in yellow.