This commit introduces vector-drawn Icon implementations for the icons used in the window system's Windows 8 Look-and-Feel. Specifically, this replaces most of the bitmap icons that are used on Windows from the o.n.swing.tabcontrol and openide.awt modules.
An abstract class VectorIcon is added in the UI Utilities Module (openide.awt) as a general-purpose starting point for creating new vector icons. It handles and documents a number of tricky adjustments that are needed to draw icons that appear sharp on HiDPI screens. This class can be used to implement HiDPI icons in other LAFs at a later time, e.g. for MacOS retina displays. A small utility, VectorIconTester, was written to preview new icons at multiple resolutions, as well as to compare them with existing bitmap icons. This is less polished code that is nevertheless included here, in tabcontrol's test package. A screenshot of its output, as well as screenshots of the NetBeans IDE before and after the patch on various scaling levels, are attached to the JIRA ticket for NETBEANS-1238, and attached in this pull request below as well. To test this patch, use Windows 10 on Java 9 or Java 10, and use the workaround in https://issues.apache.org/jira/browse/NETBEANS-1227 to tell Windows to let NetBeans manage DPI scaling on its own. NetBeans screenshots before and after patch:   Output of the VectorIconTest, showing the old Windows icons next to the new scalalble ones, as well as corresponding icons on other LAFs that might have to be vectorized in the future (e.g. on MacOS):  [ Full content available at: https://github.com/apache/incubator-netbeans/pull/859 ] This message was relayed via gitbox.apache.org for [email protected]
