Updated library code to be able to store a group of nodes.
Added keyboard shortcuts:
- Del to delete selected nodes
- C to center the view
Modified paste action to paste at the center of the view.
New example (biohazard from webbzeug)
Refactored rendering of textures for save and exporting material now saves all textures.
Added an option to start a clear the project, and proper "save" and "save as..." options.
Added support for disconnects.
