Make the VIEW* parameter const. Since PCB_TEXT does a null-check,
it's not very clear if this can ever be null (and if it is,
why don't the other VIEW_ITEMs check?), so don't make them
all references too at this time.
Also dereference a few pointers a bit earlier to make non-null
promises sooner rather than later.
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
Break the non-PCB-specfic parts of PCB_REFERENCE_IMAGE out
to a common REFERENCE_IMAGE class, which is then composed into
the PCB_REFERENCE_IMAGE. This will make it easier to bring the
transform origin logic to eeschema without repetition.
This has always been possible (especially through the properties
panel with large scales), but it's even easier if the transform
origin is near a manipulated corner.
Check and reject scales that result in an overflowed image box.
This is stored as an offset from the image position,
which is the centre of the image. When interactively edited, the
transform origin stays in place. This makes it easier to scale an image
around some fixed feature in the image.
For now this is not saved out to the format, so it
reinitialises to (0, 0) each time. This means scale around
the midpoint, which is the current behaviour.
There was a gentle mish-mash of booleans, some with
true being left/right and some up/down, and some functions that
can flip in both axes (which is never actually done, and doesn't
really make geometric sense).
Replace all this with the FLIP_DIRECTION enum class, which makes
the intention completely unambiguous.
This also then allows a small scattering of simplifications,
because everything takes the same type and you don't have to
fiddle booleans to fit.
