Wiki "Getting Started" article updates

[liquid8d]

I have updated and added some additional information in the wiki article related to scripting and layout development:
https://github.com/mickelson/attract/wiki/Introduction-to-Squirrel-Programming

I also added a Tips and Tricks page which contains some useful info:
https://github.com/mickelson/attract/wiki/Scripting-Tips-and-Tricks

If you are just getting started, I recommend perusing these as there is a decent amount of info!

I just added info on classes, scripts, plugins and modules. More will be coming as I go... if you have a request or know of something that should be in there, let me know (or add it! )