Use kde-projects for kdeedu.

There's even a semi-interesting hack to force the libkdeedu to build
first.

kdesrc-buildrc-sample

@@ -337,9 +337,13 @@ end module
 
 # Educational programs.  Some are actually quite fun even if you're not trying
 # to learn anything.
-module-set
+module-set kdeedu
-    repository kde-git
+    repository kde-projects
-    use-modules libkdeedu blinken cantor kalgebra kalzium kanagram kbruch kgeography khangman kig kiten klettres kmplot kstars ktouch kturtle kwordquiz marble parley rocs step
+
+    # Until kdesrc-build supports dependency handling, you should specify
+    # submodules that should be built in order specifically, and then the
+    # parent module, which will build and remaining submodules.
+    use-modules kde/kdeedu/libkdeedu kde/kdeedu
 end module-set
 
 # Extra collection of useful plasma applets, runners, data engines, etc.