Definition Creation Fixes

[kwokcb]

Issue

Fixes: #61

• The logic for definition creation creates invalid functional graphs.
• nodegroup names are arbitrary instead of following the standard names.
• The UI labels were incorrectly calling nodegroups "category", and category identifiers were called "name".

Changes

• Update to remove inputs from the nodegraph with the currently checked in interface : addNodeDefFromNodeGraph.
• Fix up to remove undesired attributes such as node position
• Scan for available nodegroup names and only allow those to be used at creation time. Uses can modify this latter if they wish but arbtirary group names is undesired especially as this is being formalized in the specification.
• Check for duplicate definition signatures being created. Put up a warning but allow for overwrite.

Example

Modified UI example:

[manuelkoester]

Awesome! Great contribution. The drop down is a great idea :)

I also noticed that the "..." button doesn't do anything.. I'll fix that.
I would also like to see some ❔ button next to Node Group and Category telling the user what each of these mean in the context of QuiltiX and MaterialX.
I'll create an issue for this.