The launch of Google Inc.’s Android KitKat, the next version of the most widely used operating software for smartphones and tablets, is drawing near. Google executives haven’t announced a release date but people who have been briefed on KitKat say that it is coming soon. There have been several reports about KitKat’s likely features based on leaked screenshots and leaked photos of the Nexus 5 smartphone that will be the first device to show off those features. But we’ve reviewed a confidential file that Google shared with companies that make Android devices to explain the most important new features. (A Google spokeswoman didn’t respond to requests for comment.) Here’s what we know. With KitKat, Google has worked even harder to address one of Android’s biggest disadvantages versus Apple: less than half of Android devices are running the latest version of the software, called “Jelly Bean,” which was released in summer 2012.