Ensure old API still works

Since user code might already exist we keep make sure the old API still
works as well.

package/MDAnalysis/analysis/base.py

@@ -80,13 +80,8 @@ def __init__(self, trajectory, start=None,
         quiet : bool, optional
             Turn of verbosity
         """
-        self._setup_frames(trajectory, start, stop, step)
-        interval = int(self.n_frames // 100)
-        if interval == 0:
-            interval = 1
-        self._pm = ProgressMeter(self.nframes if self.nframes else 1,
-                                 interval=interval, quiet=quiet)
         self._quiet = quiet
+        self._setup_frames(trajectory, start, stop, step)
 
     def _setup_frames(self, trajectory, start=None,
                       stop=None, step=None):
@@ -97,6 +92,16 @@ def _setup_frames(self, trajectory, start=None,
         self.stop = stop
         self.step = step
         self.n_frames = len(range(start, stop, step))
+        interval = int(self.n_frames // 100)
+        if interval == 0:
+            interval = 1
+
+        # if _quiet doesn't exists because __init__ wasn't called set it to
+        # true
+        if not hasattr(self, '_quiet'):
+            self._quiet = True
+        self._pm = ProgressMeter(self.n_frames if self.n_frames else 1,
+                                 interval=interval, quiet=self._quiet)
 
     def _single_frame(self):
         """Calculate data from a single frame of trajectory

testsuite/MDAnalysisTests/analysis/test_base.py

@@ -44,6 +44,14 @@ def __init__(self, reader, **kwargs):
         super(IncompleteAnalysis, self).__init__(reader, **kwargs)
 
 
+class OldAPIAnalysis(AnalysisBase):
+    def __init__(self, reader, **kwargs):
+        self._setup_frames(reader, **kwargs)
+
+    def _single_frame(self):
+        pass
+
+
 class TestAnalysisBase(object):
     @dec.skipif(parser_not_found('DCD'),
                 'DCD parser not available. Are you using python 3?')
@@ -89,3 +97,6 @@ def test_quiet(self):
     @raises(NotImplementedError)
     def test_incomplete_defined_analysis(self):
         IncompleteAnalysis(self.u.trajectory).run()
+
+    def test_old_api(self):
+        OldAPIAnalysis(self.u.trajectory).run()