Tactile textures

These are some of the tactile textures as described and used in ["A Quantitative Perceptual Model for Tactile Roughness."](https://cs.nyu.edu/~tymms/papers/roughness_preprint.pdf) This set currently includes the bump textures, numbers 1-13.

Textures are 25x25mm flat plates with raised bumps shaped as truncated cones 1mm tall, with semi-sphere caps 0.3mm in diameter. Bumps are arranged isotropically with a prescribed average spacing from 10/16 mm to 26/16 mm. Spacings are etched on the bottom