Parametric Map Revamp

[CPBridge]

A full revamp of the highdicom.pm.ParametricMap class enabled mostly by rebasing on the highdicom.image._Image class and refactoring behaviour common to both Segmentation and ParametricMap into _Image.

To-do list for this PR:

• [x] TILED_FULL parametric maps
• [x] Passing Volumes to parametric maps
• [x] Parametric map pyramids
• [x] Allowing further source images when creating parametric maps
• [x] Automatically matching source images to frames of a parametric map based on geometry
• [x] Encoding parametric maps with multiple workers for compression
• [x] Correctly returning floating point pixel data in the highdicom.Image class
• [x] Address #168
• [ ] get_volume and get_total_pixel_matrix for parametric map
• [x] pmread function
• [ ] Tests for all above behaviour
• [ ] Quickstart example for Parametric Maps
• [ ] User Guide page on Parametric Maps