Check all hosts for use of both binary and detached label files

[rfrenchseti]

The from_file method for all hosts should take either the binary image file or the detached label file as an argument and work either way. Ideally it would try to use the detached label first to get information and use the binary header as a backup. Go through all of the files to verify the current behavior and fix as necessary.

[astrocfi]

A second part of this is it should be possible to open an image using only the detached label file without reading the image file at all. This would provide all the info needed for geometric information when the actual image data isn't required. Perhaps this could be an argument to the from_file method.

[astrocfi]

A third part would be the ability to take an index file row and use it without reading any files at all. Sort of like from_index but without actually reading the index file first.