goodbye ioinfo, hello path
makes mayavi an optional dependency
Merge pull request #464 from jabooth/mayaviopt

make mayavi an optional dependency
Merge pull request #463 from jabooth/ioinfo2path

goodbye ioinfo, hello path
use error_type='me_norm' in all tests
removes comments
Merge pull request #465 from nontas/tests_me_norm

'me_norm' error type in tests