remove jme3-blender

[neph1]

we removed jme3-blender from the build a couple of years ago, but never removed the code for some reason.

[gemini-code-assist]

Code Review

This pull request completely removes the jme3-blender module, deleting all associated source files, assets, and scripts, while updating the project configuration and bumping the version to 3.8.1-SNAPSHOT. Feedback on the changes suggests maintaining the multi-line format for the modules property in nbproject/project.properties instead of collapsing it into a single line, to preserve readability and ease of tracking future changes.

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