Oomph auto clean and xcore (#2074)

* Update StatechartTools.setup

added clean setupTask

* Update README.md

removed clean instruction

* Update README.md

added description for clean build

* Update StatechartTools.setup

added xcore
added project clean and build

StatechartTools.setup

@@ -70,6 +70,8 @@
         name="org.eclipse.xtext.sdk.feature.group"/>
     <requirement
         name="org.eclipse.m2e.feature.feature.group"/>
+    <requirement
+        name="org.eclipse.emf.ecore.xcore.sdk.feature.group"/>
     <repository
         url="${oomph.update.url}"/>
     <description>Install the tools needed in the IDE to work with the source code for ${scope.project.label}</description>
@@ -2523,5 +2525,9 @@
       xsi:type="launching:LaunchTask"
       excludedTriggers="STARTUP"
       launcher="GenerateSGen.mwe2"/>
+  <setupTask
+      xsi:type="projects:ProjectsBuildTask"
+      excludedTriggers="STARTUP"
+      clean="true"/>
   <stream name="master"/>
 </setup:Project>