Dev/decode my302 (#254)

This PR adds support for decoding digital data from the my320 test chip.
- Added BitOffset (strong type)
- Expand 24 to 32 bit 
- Python bindings for decoding my302
- Improved docs

docs/src/python/file/pyCtbRawFile.rst

@@ -0,0 +1,25 @@
+
+CtbRawFile
+============
+
+Read analog, digital and transceiver samples from a raw file containing
+data from the Chip Test Board. Uses :mod:`aare.transform` to decode the 
+data into a format that the user can work with. 
+
+.. code:: python
+
+    import aare
+    from aare.transform import Mythen302Transform
+    my302 = Mythen302Transform(offset = 4)
+
+    with aare.CtbRawFile(fname, transform = my302) as f:
+    for header, data in f:
+       #do something with the data
+
+.. py:currentmodule:: aare
+
+.. autoclass:: CtbRawFile
+    :members:
+    :undoc-members:
+    :show-inheritance:
+    :inherited-members: