Godot 3.0 compatible

This update finally brings SMRT to the assetlib, completely ported over to godot 3.x

SMRT-Godot's runtime systems have been compatible with godot 3 since july, except some minor bugs(like the audio playback) and the editor. I've left SMRT-Godot in beta for quite some time and now, it is finally time to let it go into the assetlib.
This means basically that:

• if you're still in godot 2.x, you have no need to update as this has no new features, it is simply a port to 3.0 and if you update, you will break your working game
• If you still wish to use godot 2.x on future projects( hey, I'm not judging, godot is this godot), you'll need to grab the 2.0 version directly from github.
• And a version bump to make SMRT's main release number be more easily understood

Special thanks to @ellis-matthew4