Switch master to v0.2.1-dev
Update to "Why xray" doc page (including figure)
Merge pull request #215 from shoyer/why-xray

Update to "Why xray" doc page (including figure)
Fix two documentation typos
Tweaks to why-xray
Major reorganization of internal modules

Most of xray -> xray.core. xray.backends -> xray.io.
Remove circular dependencies from xray.core
Move tests to xray/test and update setup.py
All relative imports in xray.io
Move squeeze from utils to common
Split formatting off from common.py
Split off new core.alignment module
remove unnecessary compat in test/test_io.py
Update .travis.yml

Test 3.4

Make the pydap tests optional
Move io back to backends
Reorder pydap test to the end so it does not block other tests
use conda instead of pip to install unittest2
Merge pull request #216 from shoyer/reorg

Internal code reorganization; creates xray.core module
Fix truncation from concat on fixed length str dtypes
Speedup Variable.concat

On this toy benchmark, these changes speed up execution from 240ms to 153ms:

    xs = [xray.Variable('x', [i]) for i in range(10000)]
    %timeit xray.Variable.concat(xs, 'x')