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:

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