Update extension template and feature enhacements

[sadhana-r]

This PR includes the following changes:

• Updates the Bone Texture extension to utilize parameter nodes
• Combines the serialize mode features within the main extension (and removes the separate serializer module)
• Fixes bugs in the bone texture computation
• Removes the option to save texture colormaps as CSV files. Is that option needed?
• Allows user to specify the csv filename when saving computed features.
• Adds the ability to compute textures across an entire image (without a segmentation mask)

[bpaniagua]

A few notes:

• Simplify extension and reduce redundancy by adding serializing features to Bone Texture. Include an option in the input menu that allow to choose if you are running for a single scan or a collection of scans (after parsing a directory).
• Add export menu to Bone Texture module. It would be great to have the "separate feature maps" as part of the Bone Texture extension, right now they are part of the serializer only.

[bpaniagua]

#47