RawSubFile support multi file access (#173)

This PR is a fix/improvement to a problem that Jonathan had. (#156) The
original implementation opened all subfiles at once witch works for
normal sized datasets but fails at a certain point (thousands of files).

- This solution uses RawSubFile to manage the different file indicies
and only opens the file we need
- Added logger.h from slsDetectorPackage for debug printing (in
production no messages should be visible)

python/tests/test_RawSubFile.py

@@ -5,32 +5,35 @@ from aare import RawSubFile, DetectorType
 
 @pytest.mark.files
 def test_read_a_jungfrau_RawSubFile(test_data_path):
+
+    # Starting with f1 there is now 7 frames left in the series of files
     with RawSubFile(test_data_path / "raw/jungfrau/jungfrau_single_d0_f1_0.raw", DetectorType.Jungfrau, 512, 1024, 16) as f:
-        assert f.frames_in_file == 3
+        assert f.frames_in_file == 7
 
         headers, frames = f.read()
 
-    assert headers.size == 3
-    assert frames.shape == (3, 512, 1024)
+    assert headers.size == 7
+    assert frames.shape == (7, 512, 1024)
     
-    # Frame numbers in this file should be 4, 5, 6
-    for i,h in zip(range(4,7,1), headers):
+
+    for i,h in zip(range(4,11,1), headers):
         assert h["frameNumber"] == i
 
     # Compare to canned data using numpy
     data = np.load(test_data_path / "raw/jungfrau/jungfrau_single_0.npy")
-    assert np.all(data[3:6] == frames)
+    assert np.all(data[3:] == frames)
 
 @pytest.mark.files
 def test_iterate_over_a_jungfrau_RawSubFile(test_data_path):
 
     data = np.load(test_data_path / "raw/jungfrau/jungfrau_single_0.npy")
 
+    # Given the first subfile in a series we can read all frames from f0, f1, f2...fN
     with RawSubFile(test_data_path / "raw/jungfrau/jungfrau_single_d0_f0_0.raw", DetectorType.Jungfrau, 512, 1024, 16) as f:
         i = 0
         for header, frame in f:
             assert header["frameNumber"] == i+1
             assert np.all(frame == data[i])
             i += 1
-        assert i == 3
-        assert header["frameNumber"] == 3
+        assert i == 10
+        assert header["frameNumber"] == 10