Adding Experimental Blender 2.80 Support

I have attempted to implement basic support for blender 2.80, since it appears many people are migrating to this new version, and I have interest in using it myself. Unfortunately, the new blender API is significantly different, and so these changes are not really backwards compatible. To account for this, I made new plugin files specifically designed for blender 2.80, so that people still on 2.79 can still use the existing ones for the time being. The new files are largely the same as the existing files, but have significant differences due to the changes in the new blender API. If you'd like to see what actually changed between versions, I'd recommend comparing the old and new files in something like diffchecker or some other diff tool. Also, If you would like to implement a different method for versioning, I would be open to suggestions!

There are a few things I still haven't quite figured out while trying to migrate these plugins. The main features that I know are not working are Alt Textures, and Vertex Colors.The old logic for them is still there, but is currently commented out. I also didn't test this super thoroughly, so there may still be some issues to work out.

Note: To be honest, I'm not super familiar with python or with blender APIs, so any feedback or suggestions are welcome!