[wmlunits] Don't start more than one convert process at a time...

Starting many at once will stall CPUs and IO, and if delayed (so there
are 100ds or 1000ds of processes running at the same time) possibly
require massive amounts of memory.

data/tools/unit_tree/TeamColorizer

@@ -92,6 +92,7 @@ if __name__ == '__main__':
     if verbose:
         print convertor + " '" + infilename + "' '" + outfilename + "'"
     if not dryrun:
-        Popen(convertor.split() + [infilename, outfilename])
+        p = Popen(convertor.split() + [infilename, outfilename])
+        p.wait()
 
 # TeamColorizer ends here.

data/tools/unit_tree/helpers.py

@@ -135,7 +135,8 @@ class ImageCollector:
                 # helpers.py currently executing.
                 command = os.path.join(os.path.dirname(__file__),
                     "TeamColorizer")
-                Popen([command, ipath, opath])
+                p = Popen([command, ipath, opath])
+                p.wait()
             else:
                 sys.stderr.write(
                     "Warning: Required image %s: \"%s\" does not exist.\n" % (c, i))