Previously we only had `Point::end_point_for_square_aspect_ratio`,
which was convenient for PixelPaint but assumed the aspect ratio
was always fixed at 1. This patch replaces it with a new mthod that
takes in an arbitrary aspect ratio and computes the end point based
off that.
There's some explicit casting going on in `Point.cpp` to ensure that
the types line up, since we're templating Point based on `T`.`
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
