RoboVM maintenance: keeping up to date

Today maintenance PR326 delivers following:

• fixes gradle’s ` Warning: org.robovm.apple.uikit.UIWindow is a phantom class! [issue](https://gitter.im/MobiVM/robovm?at=5b98e2c4f3c26b08f6664e07) when using v4 and implementation` as dependency command. This was happening due using outdated configuration name in dependency path resolution:

// configure the runtime classpath
Set<File> classpathEntries = project.getConfigurations().getByName("runtime").getFiles();

while

 // The name of the "runtime" configuration. This configuration is deprecated and doesn't represent a correct view of
 // the runtime dependencies of a component.

• update to Idea 2018.2.3: fixes broken Idea plugin build due to gradle dependencies needs to be specified
• update to Xcode10: sdk 10.14 and removed x86 mac target as deprecated and breaks build process