Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
The center point on polygons now maintains the axis of the dragged line
and, optionally with Ctrl pressed, maintains the slope of the adjacent
segments as well.
This also fixes a longstanding issue that prevented the ctrl-snapping
from using the original point rather than the last updated point when
constraining.
Fixes https://gitlab.com/kicad/code/kicad/issues/2465
