Use more Into<Point> instead of Point for arguments

[sagudev]

We already did for most of Point arguments. This is especially relevant for users of euclid now that we have #463.

[sagudev]

It would be nice to also do this on traits (Shape, paramcurves*), but that would be breaking change.

[tomcur]

I'm cautiously in favor of doing this for Point, but we may want to make sure we only do this for types whose From impls are free (within the confines of this crate). Otherwise the API would hide conversions that could potentially needlessly slow down user code, if the same conversions are performed multiple times.

From<TranslateScale> for Affine is not quite free, and, e.g., for Rect (not included here), From<(Point, Size)> and From<euclid::Rect<f64, UnknownUnit>> aren't free.

[sagudev]

I'm cautiously in favor of doing this for Point, but we may want to make sure we only do this for types whose From impls are free (within the confines of this crate). Otherwise the API would hide conversions that could potentially needlessly slow down user code, if the same conversions are performed multiple times.

From for Affine is not quite free, and, e.g., for Rect (not included here), From<(Point, Size)> and From<euclid::Rect<f64, UnknownUnit>> aren't free.

I agree. I forgot that From<TranslateScale> for Affine existed. Will drop last commit.

[tomcur]

Thanks!