Made fileno transparent
prevent memmap being created from .bz2 file
NF: add assert_data_similar function

Thinking about testing real example images against recorded information
about these images, maybe from previous loads, or loads by other
software.

This helper function tests against recorded (previous) loaded data if
present, or recorded summary statistics otherwise.
RF: refactor image API classes

Refactor the image API testing classes to:

* make it clearer how to add one;
* allow testing with example images.
RF+TST: use new API to test MINC image load

Refactor MINC tests to use example image format from the image API
validation code.

Add these these examples to the image API validation tests.
RF+TST: add image API tests for PARREC

Use image validator API to test API of loaded PARREC images.
FIX: Minor fixes to clean up tests in windows
FIX: Py3k on Linux fixes
STY: PEP8
Merge pull request #263 from Eric89GXL/win-fixes

MRG: Minor fixes to clean up tests in windows

Various PEP8 changes and context manager suppression of warnings.
DOC: docstring for PARRECArrayProxy
TST: make truncated PAR/REC and test

Test that truncated PAR/REC file raises error or warning according to
`permit_truncated` flag.
RF+TST: add permit_truncated to header; fix copy

Add `permit_truncated` to header attributes. Fix `copy` method to use
value of `permit_truncated` when making a copy. Test.
RF+TST: standard file loading methods for PARREC

Add methods with optional args `permit_truncated` and `scaling`:

* from_file_map
* from_filename
* load
NF: add keyword-only decorator with tests

Add decorator to make keyword arguments keyword-only for Python 2.
RF: refactor PARREC file meths for keyword only

Use and test keyword-onliness of permit_truncated, scaling argument to
PARRECImage file loading methods.
Merge pull request #264 from matthew-brett/parrec-fix-refactor

MRG: some refactoring of PARREC API

Add fake truncated file for testing, and test.
Add permit_truncated as header attribute.
Fix header copy to use permit_truncated.
Add file loading API methods with PARREC-specific parameters.
Make PARREC-specific parameters keyword-only.
RF: refactor tests for setting header dtype

Refactor imports; create new header for each dtype set test; extend
tests to check dtype and swapped dtype; extend tests to check all
supported numerical types for particular header type.
NF: hdr dtype can be str code / int / float

Allow 'set_data_dtype' method of Analyze header types to use string
codes like 'i1', 'f8', and Python types like float and int.
RF: indent dtype test code block

From review by Eric Larson