bitbake: implement command to get all possible targets and their dependencies

Add a new command generateTargetsTree() which returns a dependency tree of
possible targets (tasks and recipes) as well as their dependency information.

Optional parameter 'klass' also ensures any recipes which inherit the
specified class path (i.e. 'classes/image.bbclass') are included in the model

Signed-off-by: Joshua Lock <josh@linux.intel.com>

bitbake/lib/bb/command.py

@@ -222,6 +222,16 @@ class CommandsAsync:
         command.finishAsyncCommand()
     generateDotGraph.needcache = True
 
+    def generateTargetsTree(self, command, params):
+        """
+        Generate a tree of all buildable targets.
+        """
+        klass = params[0]
+
+        command.cooker.generateTargetsTree(klass)
+        command.finishAsyncCommand()
+    generateTargetsTree.needcache = True
+
     def showVersions(self, command, params):
         """
         Show the currently selected versions