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/index.rst

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+File I/O
+===================
+
+.. toctree::
+   :caption: File I/O
+   :maxdepth: 1
+
+   pyClusterFile
+   pyCtbRawFile
+   pyFile
+   pyJungfrauDataFile
+   pyRawFile
+   pyRawMasterFile
+   pyTransform

docs/src/python/file/pyClusterFile.rst

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+
+ClusterFile
+============
+
+
+The :class:`ClusterFile` class is the main interface to read and write clusters in aare. Unfortunately the
+old file format does not include metadata like the cluster size and the data type. This means that the
+user has to know this information from other sources. Specifying the wrong cluster size or data type
+will lead to garbage data being read. 
+
+.. py:currentmodule:: aare
+
+.. autoclass:: ClusterFile
+    :members:
+    :undoc-members:
+    :inherited-members:
+
+
+Below is the API of the ClusterFile_Cluster3x3i but all variants share the same API.
+
+.. autoclass:: aare._aare.ClusterFile_Cluster3x3i
+    :special-members: __init__
+    :members:
+    :undoc-members:
+    :show-inheritance:
+    :inherited-members:

docs/src/python/file/pyCtbRawFile.rst

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+
+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:

docs/src/python/file/pyFile.rst

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+
+File
+========
+
+.. py:currentmodule:: aare
+
+.. autoclass:: File
+    :members:
+    :undoc-members:
+    :show-inheritance:
+    :inherited-members:

docs/src/python/file/pyJungfrauDataFile.rst

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+JungfrauDataFile
+===================
+
+.. py:currentmodule:: aare
+
+.. autoclass:: JungfrauDataFile
+    :members:
+    :undoc-members:
+    :show-inheritance:
+    :inherited-members:

docs/src/python/file/pyRawFile.rst

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+RawFile
+===================
+
+.. py:currentmodule:: aare
+
+.. autoclass:: RawFile
+    :members:
+    :undoc-members:
+    :show-inheritance:
+    :inherited-members:

docs/src/python/file/pyRawMasterFile.rst

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+RawMasterFile
+===================
+
+.. py:currentmodule:: aare
+
+.. autoclass:: RawMasterFile
+    :members:
+    :undoc-members:
+    :show-inheritance:
+    :inherited-members:

docs/src/python/file/pyTransform.rst

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+Transform
+===================
+
+The transform module takes data read by :class:`aare.CtbRawFile` and decodes it
+to a useful image format. Depending on detector it supports both analog
+and digital samples. 
+
+For convenience the following transform objects are defined with a short name
+
+.. code:: python
+
+    moench05 = Moench05Transform()
+    moench05_1g = Moench05Transform1g()
+    moench05_old = Moench05TransformOld()
+    matterhorn02 = Matterhorn02Transform()
+    adc_sar_04_64to16 = AdcSar04Transform64to16()
+    adc_sar_05_64to16 = AdcSar05Transform64to16()
+
+.. py:currentmodule:: aare
+
+.. automodule:: aare.transform
+    :members:
+    :undoc-members:
+    :private-members:
+    :special-members: __call__
+    :show-inheritance:
+    :inherited-members: