Windows 10 build 10586 (th2 release)

This build is a candidate for release as the Windows 10 Fall Update. It contains fit-and-finish improvements and bugfixes, but few, if any, new features are included. The bugs that plagued many earlier TH2 builds have been fixed, and this build is the first in quite some time to be a good daily driver. The only noteworthy changes in this build are as follows:
 * The preview watermark has been removed.
 * The preview license has been substituted for the RTM EULA used in build 10240.