#409 Corrections to fill pattern generation and density checks in magic. Pull request opened by RTimothyEdwards Made a number of changes in support of pattern fill generation and density checks. Modified the tech file parameters for the generated fill to center the fill-related density on 50% fill. Corrected an issue with failure to generate poly fill on top of diffusion fill, and then to ensure that the poly fill shape is centered on the diffusion fill shape. Added different position offsets to each of the metal fill layers so they are not stacked directly on top of one another. Corrected the expressions for calculating the pro-rated densities on the right and top edge of a layout. Added some documentation of pattern fill and density checks to the README file, and updated the RELEASE_NOTES file. Fixes #408 • Tests pass • Appropriate changes to README are included in PR Signed-off-by: R. Timothy Edwards tim@opencircuitdesign.com IHP-GmbH/IHP-Open-PDK