Magick.NET 7.0.6.0

Breaking changes in Magick.NET:

• The Core NuGet packages are now part of the normal packages.

Related changes in ImageMagick since the last release of Magick.NET:

• coders/png.c: Accept exIf chunks whose data segment erroneously begins with "Exif\0\0".
• Removed experimental PNG zxIF chunk support; the proposal is dead.
• Fix choppy bitmap font rendering (reference https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=32071)
• The +opaque option is not longer a noop (reference https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=32081).
• Add support for 'hex:' property.