Ignore generated *.egg-info/* files
Fix minor copy/paste error in read_header docstring
_validate_magic_line: Fix ValueError exception catching, add doctests
Rename separate_header to detached_header for consistency with NRRD spec
read_header: Fix reading NRRD with attached header

Due to incorrect comparison of object identities rather than values.
read_header: More generalized string representation of invalid fields
Add some basic first unit tests using unittest
Fix support for 'byte skip' field identifier
read_data: add seek_past_header parameter, fix skipline for compressed data

Also add unit tests to demonstrate the fixes and a unit test for
(currently broken) bz2 compression support
Fix bz2 compression support