Multiproject builds - org.gradle.api.InvalidUserDataException: Cannot add task ':subproj:decompile' as a task with that name already exists.

Seems to be caused by BasePlugin.project being static and trying to create that all it's tasks in the same project multiple times.

I've tried changing it to a normal field and it seems to at least let the build run, currently testing if it broke anything, will send a PR once i'm sure.

Full error:

```
* Exception is:
org.gradle.api.ProjectConfigurationException: A problem occurred configuring root project 'gendustry2'.
	at org.gradle.configuration.project.LifecycleProjectEvaluator.addConfigurationFailure(LifecycleProjectEvaluator.java:79)
	at org.gradle.configuration.project.LifecycleProjectEvaluator.notifyAfterEvaluate(LifecycleProjectEvaluator.java:74)
	at org.gradle.configuration.project.LifecycleProjectEvaluator.evaluate(LifecycleProjectEvaluator.java:61)
	at org.gradle.api.internal.project.AbstractProject.evaluate(AbstractProject.java:507)
	at org.gradle.api.internal.project.AbstractProject.evaluate(AbstractProject.java:82)
	at org.gradle.configuration.DefaultBuildConfigurer.configure(DefaultBuildConfigurer.java:31)
	at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:142)
	at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:113)
	at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:81)
	at org.gradle.launcher.exec.InProcessBuildActionExecuter$DefaultBuildController.run(InProcessBuildActionExecuter.java:64)
	at org.gradle.launcher.cli.ExecuteBuildAction.run(ExecuteBuildAction.java:33)
	at org.gradle.launcher.cli.ExecuteBuildAction.run(ExecuteBuildAction.java:24)
	at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:35)
	at org.gradle.launcher.exec.InProcessBuildActionExecuter.execute(InProcessBuildActionExecuter.java:26)
	at org.gradle.launcher.cli.RunBuildAction.run(RunBuildAction.java:50)
	at org.gradle.api.internal.Actions$RunnableActionAdapter.execute(Actions.java:171)
	at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:201)
	at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:174)
	at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:170)
	at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:139)
	at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:33)
	at org.gradle.launcher.cli.ExceptionReportingAction.execute(ExceptionReportingAction.java:22)
	at org.gradle.launcher.Main.doAction(Main.java:46)
	at org.gradle.launcher.bootstrap.EntryPoint.run(EntryPoint.java:45)
	at org.gradle.launcher.Main.main(Main.java:37)
	at org.gradle.launcher.bootstrap.ProcessBootstrap.runNoExit(ProcessBootstrap.java:50)
	at org.gradle.launcher.bootstrap.ProcessBootstrap.run(ProcessBootstrap.java:32)
	at org.gradle.launcher.GradleMain.main(GradleMain.java:23)
	at org.gradle.wrapper.BootstrapMainStarter.start(BootstrapMainStarter.java:30)
	at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:127)
	at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:58)
Caused by: org.gradle.api.InvalidUserDataException: Cannot add task ':bdlib:decompile' as a task with that name already exists.
	at org.gradle.api.internal.tasks.DefaultTaskContainer.create(DefaultTaskContainer.java:60)
	at org.gradle.api.internal.project.AbstractProject.task(AbstractProject.java:950)
	at net.minecraftforge.gradle.common.BasePlugin.makeTask(BasePlugin.java:153)
	at net.minecraftforge.gradle.common.BasePlugin.makeTask(BasePlugin.java:144)
	at net.minecraftforge.gradle.user.UserBasePlugin.delayedTasks(UserBasePlugin.java:204)
	at net.minecraftforge.gradle.user.UserBasePlugin.afterEvaluate(UserBasePlugin.java:667)
	at net.minecraftforge.gradle.user.ForgeUserPlugin.afterEvaluate(ForgeUserPlugin.java:45)
	at net.minecraftforge.gradle.common.BasePlugin$1.execute(BasePlugin.java:52)
	at net.minecraftforge.gradle.common.BasePlugin$1.execute(BasePlugin.java:48)
	at org.gradle.listener.BroadcastDispatch$ActionInvocationHandler.dispatch(BroadcastDispatch.java:105)
	at org.gradle.listener.BroadcastDispatch$ActionInvocationHandler.dispatch(BroadcastDispatch.java:94)
	at org.gradle.listener.BroadcastDispatch.dispatch(BroadcastDispatch.java:79)
	at org.gradle.listener.BroadcastDispatch.dispatch(BroadcastDispatch.java:31)
	at org.gradle.messaging.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:93)
	at com.sun.proxy.$Proxy13.afterEvaluate(Unknown Source)
	at org.gradle.configuration.project.LifecycleProjectEvaluator.notifyAfterEvaluate(LifecycleProjectEvaluator.java:67)
	... 29 more
```