(abstract)card, its views and layout improvements
Card sets size and position in gridview by doing calculations in every widget on every width change. A cardWidth and cardHeight seems a better solution especially in a view. This might have a little performance improvement. I made 2 more templates with a little documentation for people that want to make a custom grid view or custom card widget and added more options to DefaultCardBackground and BannerImage for better customization. Sorry for not so good merge title, description and bad commit names. I am quite new to this.